This is Info file pm.info, produced by Makeinfo version 1.68 from the input file bigpm.texi.  File: pm.info, Node: C/DynaLib/Struct, Next: C/Scan, Prev: C/DynaLib, Up: Module List Tool for handling the C `struct' data type ****************************************** NAME ==== C::DynaLib::Struct - Tool for handling the C `struct' data type SYNOPSIS ======== use C::DynaLib::Struct; Define C::DynaLib::Struct( $struct_tag, $template0, \@field_names0, [$template1, \@field_names1,] ... ); $rstruct = tie( $struct, $struct_tag [, @initializer_list] ); $value = $rstruct->my_field(); $rstruct->my_field( $new_value ); $pointer_to_struct = pack( 'p', $struct ); $struct = $new_struct; # assigns all fields at once # after passing pointer-to-struct to a C function: $rstruct->Unpack(); $returned_value = $rstruct->my_field(); DESCRIPTION =========== When mixing Perl and C, the conversion of data types can be rather tedious and error-prone. This module provides an abstraction from Perl's pack and unpack operators for using structures whose member data types and positions do not change. Here are some examples of C code that deals with a `struct'. On the right are some possible Perl equivalents. C Perl - ---- typedef struct { use C::DynaLib::Struct; int m_int; Define C::DynaLib::Struct( double m_double; 'Foo', char * m_string; 'i' => ['m_int'], } Foo; 'd' => ['m_double'], 'p' => ['m_string'] ); # or, equivalently, Define C::DynaLib::Struct('Foo', 'idp', [qw(m_int m_double m_string)]); Foo foo; Foo *pfoo = &foo; $rfoo = tie ($foo, 'Foo'); i = pfoo->m_int; $i = $rfoo->m_int; d = foo.m_double; $d = (tied $foo)->m_double; pfoo->m_string = "hi"; $rfoo->m_string("hi"); Foo bar; tie ($bar, 'Foo'); bar = foo; $bar = $foo; void do_foo(Foo *arg); use C::DynaLib; $lib = new C::DynaLib("-lfoo"); $do_foo = $lib->DeclareSub("do_foo","","P"); # or you could write an XSUB. do_foo(&foo); &$do_foo($foo); returned_i = foo.m_int; $rfoo->Unpack(); $returned_i = $rfoo->m_int; BUGS ==== Data member access is through autoloaded methods, so actual existing methods are not allowed as structure member names. Currently, the illegal names are AUTOLOAD, TIESCALAR, FETCH, STORE, and Unpack. The names of Structs themselves must be allowable package names. Using an existing package name will cause problems. `struct's mean different things to different C compilers on different machines. Use caution when assigning pack codes to C data types. SEE ALSO ======== perlfunc(1) (for pack), perlref(1), perltie(1).  File: pm.info, Node: C/Scan, Next: CArray, Prev: C/DynaLib/Struct, Up: Module List scan C language files for easily recognized constructs. ******************************************************* NAME ==== C::Scan - scan C language files for easily recognized constructs. SYNOPSIS ======== $c = new C::Scan 'filename' => $filename, 'filename_filter' => $filter, 'add_cppflags' => $addflags; $c->set('includeDirs' => [$Config::Config{shrpdir}]); my $fdec = $c->get('parsed_fdecls'); DESCRIPTION =========== *This description is *VERY* incomplete.* This module uses `Data::Flow' interface, thus one uses it in the following fashion: $c = new C::Scan(attr1 => $value1, attr2 => $value2); $c->set( attr3 => $value3 ); $value4 = $c->get('attr4'); Attributes are depending on some other attributes. The only required attribute, i.e., the attribute which should be set, is filename, which denotes which file to parse. All other attributes are either optional, or would be calculated basing on values of required and optional attributes. Output attributes ----------------- `includes' Value: reference to a list of included files. `defines_args' Value: reference to hash of macros with arguments. The values are references to an array of length 2, the first element is a reference to the list of arguments, the second one being the expansion. Newlines are not unescaped, thus #define C(x,y) E\ F will finish with `("C" => [ ["x", "y"], "E\nF"])'. `defines_no_args' Value: reference to hash of macros without arguments. Newlines are not escaped, thus #define A B will finish with `("A" => "B")'. `fdecls' Value: reference to list of declarations of functions. `inlines' Value: reference to list of definitions of functions. `parsed_fdecls' Value: reference to list of parsed declarations of functions. A parsed declaration is a reference to a list of `(rt, nm, args, ft, mod)'. Here rt is return type of a function, `nm' is the name, args is the list of arguments, `ft' is the full text of the declaration, and mod is the modifier (which is always undef). Each entry in the list args is of the same form `(ty, nm, args, ft, mod)', here `ty' is the type of an argument, `nm' is the name (a generated one if missing in the declaration), args is undef, and mod is the string of array modifiers. `typedef_hash' Value: a reference to a hash which contains known `typedef's as keys. Values of the hash are array references of length 2, with what should be put before/after the type for a standalone typedef declaration (but without the `typedef' substring). Parse uses naive heuristics. `typedef_texts' Value: a reference to a list which contains known expansions of `typedef's. `typedefs_maybe' Value: a reference to a list of `typedef'ed names. Heuristics are used. `vdecls' Value: a reference to a list of `extern' variable declarations. `vdecl_hash' Value: a reference to a hash of parsed `extern' variable declarations, containing the variable names as keys. Values of the hash are array references of length 2, with what should be put before/after the name for a standalone extern variable declaration (but without the `extern' substring). `typedef_structs' Value: a reference to a hash of parsed struct declarations from typedefs. Keys are typedefed names, values are undef if not a struct or union, else an array reference of definitions of the elements of the structure; each definition is itself an array reference of length 3, consisting of what should be put before/after the name for a standalone variable declaration, followed by the name of the element. Anonymous structs and unions used within the definitions are given an arbitrary name including the string `ANON', and referred to using that name.  File: pm.info, Node: CArray, Next: CDB_File, Prev: C/Scan, Up: Module List External C Arrays for Perl (Alpha) ********************************** NAME ==== CArray - External C Arrays for Perl (Alpha) SYNOPSIS ======== use CArray; $dblarr = new CDoubleArray(1000); @values = (0..1000); $dblarr = new CIntArray(1000,\@values); ref $dblarr eq 'CIntArray' and $dblarr->set(0,1) and $dblarr->get(0) == 1; tie (@array, 'CDoubleArray', 1000, \@values); print $array[0], join ', ', @dbl[1..20]; DESCRIPTION =========== Several XS classes and methods to deal with unstructured continuous C arrays are provided, for the three basic C-types array of *INT*, *DOUBLE* and STRING and some aggregate types int[2][], int[3][], int[4][], double[2][], double[3][] as range checked, tieable arrays. This roughly reflects to: CArray CIntArray int[] CInt2Array int[][2] CInt3Array int[][3] CInt4Array int[][4] CDoubleArray double[] CDouble2Array double[][2] CDouble3Array double[][3] CStringArray *char[] External C arrays limit communication overhead with large simple data structures, where size or time constraints become serious, optionally manipulated by external XS modules. Such as various computional geometry modules dealing with 10.000 - 200.000 double[3]. Modification is done in-place and preferably in bulk. It might also be easier to write XSUBs by converting the data to CArray's before, pass this pointer to the C func, and handle the results in Perl then. The Fetch/Store operations with tied arrays copy the scalars to perl and back, so it shouldn't be abused for BIG data. Perl's safemalloc/safefree is used. CLASS METHODS ============= new ( SIZE, [ ARRAYREF ] ) The new method is provided for all classes, the optional arrayref arg applies only to the base Array classes, not the aggregate. The constructor creates a new `CArray' object. For the Array classes the second optional argument is used to initialize it with an array. If the provided arrayref is shorter that the allocated size, the rest will stay uninitialized. $D = new CDoubleArray(1000,[0..999]); init ( values ) A seperate init method for bulk definitions. (fill) This is the same as the second new argument. If the provided values arrayref is shorter that the allocated size, the rest will stay uninitialized. $I = CIntArray::new(100) ; $I->init( [0..99] ); len () The len method returns the length of the array, 1+ the index of the last element. To enlarge the array grow() should be used. $D = new CDoubleArray(5000); for my $j (0 .. $D->len-1) { $D->set($_, 0.0)); } $D->len; # => 5000 get ( index ) get returns the value at the given index, which will be scalar or a list. Croaks with "index out of range" on wrong index. $I = new CIntArray(2,[0,1]); print $I->get(1); # => 1 print $I->get(2); => croak "index out of range" $I2 = new CInt2Array(2,[[0,1]]); print $I->get(0); # => (0 1) set ( index, value ) The set method is provided for all classes. It changes the value at the given index. The value should be either a scalar or an arrayref. Croaks with "index out of range" on wrong index. Returns nothing. $I = new CIntArray(100); map { $I->set($_,$i[$_]) } (0..99); $I->set(99,-1); $I->set(100); => "index out of range" $I2 = CInt2Array->new(2); $I2->set(0, [1,0]); $I2->set(1, [0,1]); list () Returns the content of the flat array representation as arrayref. grow ( n ) Adds room for n elements to the array. These elements must be initialized extra with set. To support faster grow() a certain number of already pre-allocated items at the end of the array will be used. (see free) Returns nothing. delete ( index ) Deletes the item at the given index. free is incremented and the remaining array items are shifted. Returns nothing. get_grouped_by ( size, index ) Returns a list of subsequent values. It returns a list of size indices starting at size * index. This is useful to abuse the unstructured array as typed array of the same type, such as *double[3] or *int[2]. But this is normally not used since fast get methods are provided for the sequential classes, and those methods can be used on flat arrays as well. (Internally all sequential arrays are flat). CInt3Array::get($I,0) == $I->get_grouped_by(3,0) $ptr->get_grouped_by(2,4) returns the 4-th pair if the array is seen as list of pairs. $ptr->get_grouped_by(3,$i) => (ptr[i*3] ptr[i*3+1] ptr[i*3+2] ) slice ( start, size, [ stride=1 ] ) C++ like slice operator on a flat array. - In contrast to get_grouped_by() which semantics are as on a grouped array. Returns a list of size items, starting at start, with interim offsets of stride which defaults to 1. This is useful to return columns or rows of a flat matrix. $I = new CIntArray (9, [0..8]); $I->slice ( 0, 3, 3 ); # 1st column => (0 3 6) $I->slice ( 0, 3, 1 ); # 1st row => (0 1 2) $I->get_grouped_by(3, 0); => (0 1 2) isort () "Indirect sort", numerically ascending only. Returns a fresh sorted index list of integers (0 .. len-1) nreverse () "Reverse in place". (The name comes from lisp, where n denotes the destructive version). Destructively swaps all array items. Returns nothing. SEQUENTIAL CLASSES and CONVERSION ================================= To mix and change parallel and sequential data structures, the aggregate (ie sequential) types are derived from their base classes with fast get and set methods to return and accept lists instead of scalars. The Arrays for Int2, Int3, Int4, Double2 and Double3 can also be converted from and to their base objects with fast XS methods. # three parallel CIntArray's $X = new CIntArray(1000); $Y = new CIntArray(1000); $Z = new CIntArray(1000); # copy to one sequential *int[3], new memory $I = $X->ToInt3($Y,$Z); # or to an existing array $I = new CIntArray(3000); $I = $X->ToInt3($Y,$Z,$I); # copies back with allocating new memory ($X, $Y, $Z) = $I->ToPar(); # copies back with reusing some existing memory (not checked!) ($X, $Y, $Z) = $I->ToPar($X,$Z); # Note: I3 will be fresh. ToPar ( SeqArray, [ CArray,... ] ) This returns a list of CArray objects, copied from the sequential object to plain parallel CArray objects. This is a fast slice. *int[2] => (*int, *int) CInt2Array::ToPar CInt3Array::ToPar CInt4Array::ToPar CDouble2Array::ToPar CDouble3Array::ToPar If the optional CArray args are given the memory for the returned objects are not new allocated, the space from the given objects is used instead. To$Type$Num ( CArray, ..., [ CArray ] ) This returns a sequential CArray object copied from the parallel objects given as arguments to one sequential CArray. This is a fast map. *int, *int => *int[2] CIntArray::ToInt2 CIntArray::ToInt3 CIntArray::ToInt4 CDoubleArray::ToDouble2 CDoubleArray::ToDouble3 If the last optional CArray arg is defined the memory for the returned object is not new allocated, the space from the given object is used instead. INTERNAL METHODS ================ DESTROY () This used to crash on certain DEBUGGING perl's, but seems to be okay now. Returns nothing. CArray::itemsize ( ) CStringArray::itemsize ( [index] ) Returns the size in bytes per item stored in the array. This is only used internally to optimize memory allocation and the free list. A CStringArray object accepts the optional index argument, which returns the string length at the given index. Without argument it returns the size in bytes of a char * pointer (which is 4 on 32 bit systems). copy () Returns a freshly allocated copy of the array with the same contents. free () Internal only. Returns the number of free elements at the end of the array. If grow() needs less or equal than free elements to be added, no new room will be allocated. This is primarly for performance measures. TIEARRAY METHODS ================ *Not tested yet!* tie (var, type, size) After tying a array variable to an `CArray' class the variable can be used just as any normal perl array. tie (@array, 'CDoubleArray', 200); print $array[200]; => croak "index out of range" SEE ALSO ======== http://xarch.tu-graz.ac.at/home/rurban/software/perl or ftp://xarch.tu-graz.ac.at/pub/autocad/urban/perl `perlxs(1)' in this node, `tie', *Note Perlfunc: (perl.info)perlfunc,, Tie::Array, Geometry::Points, C::Dynalib::Poke AUTHOR ====== Reini Urban COPYRIGHT ========= Copyright (c) 1999 Reini Urban. This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. WARNING ======= These classes may be easily abused and may lead to system crashes or worse. Old: CPtr objects do no range checking at all, so may unintentionally access or overwrite foreign memory. This might only crash the system in the best case. Bad malloc'd perls or systems might also lead to destruction. The author makes NO WARRANTY, implied or otherwise, about the suitability of this software for safety or security purposes. The author shall not in any case be liable for special, incidental, consequential, indirect or other similar damages arising from the use of this software. Your mileage will vary. If in any doubt *DO NOT USE IT*. You've been warned. BUGS ==== There are certainly some. Not fully tested yet. Tests for copy, grow, delete, tie are pending. Also some more conversion tests, esp. with double and degenerate (grow, cut) cases. 1. realloc() in string_set() with DEBUGGING perl fails sometimes. 2. An implicit DESTROY invocation sometimes asserts a DEBUGGING perl, regardless if PERL_MALLOC or the WinNT msvcrt.dll malloc is used. (5.00502 - 5.00558) Esp. on perl shutdown, when freeing the extra objects at the second GC. This became much better in 0.08 than in previous versions. This is alpha, not fully tested yet! Last Changed ============ 1999/12/05  File: pm.info, Node: CDB_File, Next: CDDB, Prev: CArray, Up: Module List Perl extension for access to cdb databases ****************************************** NAME ==== CDB_File - Perl extension for access to cdb databases SYNOPSIS ======== use CDB_File; tie %h, 'CDB_File', 'file.cdb' or die "tie failed: $!\n"; $t = new CDB_File ('t.cdb', 't.tmp') or die ...; $t->insert('key', 'value'); $t->finish; CDB_File::create %t, $file, "$file.$$"; or use CDB_File 'create'; create %t, $file, "$file.$$"; DESCRIPTION =========== *CDB_File* is a module which provides a Perl interface to Dan Berstein's *cdb* package: cdb is a fast, reliable, lightweight package for creating and reading constant databases. After the tie shown above, accesses to `%h' will refer to the *cdb* file `file.cdb', as described in `tie', *Note Perlfunc: (perl.info)perlfunc,. A *cdb* file is created in three steps. First call `new CDB_File ($final, $tmp)', where `$final' is the name of the database to be created, and `$tmp' is the name of a temporary file which can be atomically renamed to `$final'. Secondly, call the insert method once for each (key, value) pair. Finally, call the finish method to complete the creation and renaming of the *cdb* file. A simpler interface to *cdb* file creation is provided by `CDB_File::create %t, $final, $tmp'. This creates a *cdb* file named `$final' containing the contents of `%t'. As before, `$tmp' must name a temporary file which can be atomically renamed to `$final'. `CDB_File::create' may be imported. EXAMPLES ======== These are all complete programs. 1. Convert a Berkeley DB (B-tree) database to *cdb* format. use CDB_File; use DB_File; tie %h, DB_File, $ARGV[0], O_RDONLY, undef, $DB_BTREE or die "$0: can't tie to $ARGV[0]: $!\n"; CDB_File::create %h, $ARGV[1], "$ARGV[1].$$" or die "$0: can't create cdb: $!\n"; 2. Convert a flat file to *cdb* format. In this example, the flat file consists of one key per line, separated by a colon from the value. Blank lines and lines beginning with *#* are skipped. use CDB_File; $cdb = new CDB_File("data.cdb", "data.$$") or die "$0: new CDB_File failed: $!\n"; while (<>) { next if /^$/ or /^#/; chop; ($k, $v) = split /:/, $_, 2; if (defined $v) { $cdb->insert($k, $v); } else { warn "bogus line: $_\n"; } } $cdb->finish or die "$0: CDB_File finish failed: $!\n"; 3. Perl version of *cdbdump*. use CDB_File; tie %data, 'CDB_File', $ARGV[0] or die "$0: can't tie to $ARGV[0]: $!\n"; while (($k, $v) = each %data) { print '+', length $k, ',', length $v, ":$k->$v\n"; } print "\n"; 4. Although a *cdb* file is constant, you can simulate updating it in Perl. This is an expensive operation, as you have to create a new database, and copy into it everything that's unchanged from the old database. (As compensation, the update does not affect database readers. The old database is available for them, till the moment the new one is finished.) use CDB_File; $file = 'data.cdb'; $new = new CDB_File($file, "$file.$$") or die "$0: new CDB_File failed: $!\n"; # Add the new values; remember which keys we've seen. while (<>) { chop; ($k, $v) = split; $new->insert($k, $v); $seen{$k} = 1; } # Add any old values that haven't been replaced. tie %old, 'CDB_File', $file or die "$0: can't tie to $file: $!\n"; while (($k, $v) = each %old) { $new->insert($k, $v) unless $seen{$k}; } $new->finish or die "$0: CDB_File finish failed: $!\n"; REPEATED KEYS ============= Most users can ignore this section. A *cdb* file can contain repeated keys. If the insert method is called more than once with the same key during the creation of a *cdb* file, that key will be repeated. Here's an example. $cdb = new CDB_File ("$file.cdb", "$file.$$") or die ...; $cdb->insert('cat', 'gato'); $cdb->insert('cat', 'chat'); $cdb->finish; Normally, any attempt to access a key retrieves the first value stored under that key. This code snippet always prints *gato*. $catref = tie %catalogue, CDB_File, "$file.cdb" or die ...; print "$catalogue{cat}"; However, all the usual ways of iterating over a hash--keys, values, and each--do the Right Thing, even in the presence of repeated keys. This code snippet prints *cat cat gato chat*. print join(' ', keys %catalogue, values %catalogue); And these two both print *cat:gato cat:chat*, although the second is more efficient. foreach $key (keys %catalogue) { print "$key:$catalogue{$key} "; } while (($key, $val) = each %catalogue) { print "$key:$val "; } The `multi_get' method retrieves all the values associated with a key. It returns a reference to an array containing all the values. This code prints *gato chat*. print "@{$catref->multi_get('cat')}"; RETURN VALUES ============= The routines tie, new, and finish return undef if the attempted operation failed; $! contains the reason for failure. DIAGNOSTICS =========== The following fatal errors may occur. (See `eval', *Note Perlfunc: (perl.info)perlfunc, if you want to trap them.) Modification of a CDB_File attempted You attempted to modify a hash tied to a *CDB_File*. CDB database too large You attempted to create a *cdb* file larger than 4 gigabytes. [ Write to | Read of | Seek in ] CDB_File failed: If *error string* is *Protocol error*, you tried to `use CDB_File' to access something that isn't a *cdb* file. Otherwise a serious OS level problem occurred, for example, you have run out of disk space. Use CDB_File::FIRSTKEY before CDB_File::NEXTKEY If you are using the NEXTKEY method directly (I can't think of a reason why you'd want to do this), you need to call FIRSTKEY first. BUGS ==== It ain't lightweight after you've plumbed Perl into it. The Perl interface to *cdb* imposes the restriction that data must fit into memory. SEE ALSO ======== cdb(3). AUTHOR ====== Tim Goodwin, , 1997-01-08 - 2000-05-30.  File: pm.info, Node: CDDB, Next: CDDB_get, Prev: CDB_File, Up: Module List a high-level interface to the Internet Compact Disc Database ************************************************************ NAME ==== CDDB.pm - a high-level interface to the Internet Compact Disc Database SYNOPSIS ======== use CDDB; ### connect to the CDDB server my $cddb = new CDDB( Host => 'www.cddb.com', # default Port => 8880, # default Login => $login_id, # defaults to %ENV's ) or die $!; ### retrieve known genres my @genres = $cddb->get_genres(); ### calculate CDDB ID based on MSF info my @toc = ( '1 0 2 37', # track, CD-i MSF (space-delimited) '999 1 38 17', # lead-out track MSF '1000 0 0 Error!', # error track (don't include if ok) ); my ($cddb_id, # used for further CDDB queries $track_numbers, # padded with 0's provided as a convenience $track_lengths, # length of each track, in MM:SS format $track_offsets, # absolute offsets (used for further CDDB queries) $total_seconds # total play time, in MM:SS format ) = $cddb->calculate_id(@toc); ### query discs based on CDDB ID and other information my @discs = $cddb->get_discs($cddb_id, $track_offsets, $total_seconds); foreach my $disc (@discs) { my ($genre, $cddb_id, $title) = @$disc; } ### query disc details (usually done with get_discs() information) my $disc_info = $cddb->get_disc_details($genre, $cddb_id); my $disc_time = $disc_info->{'disc length'}; my $disc_id = $disc_info->{discid}; my $disc_title = $disc_info->{dtitle}; my @track_offsets = @{$disc_info->{offsets}}; my @track_titles = @{$disc_info->{ttitles}}; # other information may be returned... explore! ### submit a disc (via e-mail, requires MailTools) $cddb->submit_disc ( Genre => 'classical', Id => 'b811a20c', Artist => 'Various', DiscTitle => 'Cartoon Classics', Offsets => $disc_info->{offsets}, # array reference TrackTitles => $disc_info->{ttitles}, # array reference From => 'login@host.domain.etc', # will try to determine ); DESCRIPTION =========== The CDDB serves compact disc information for programs that need it. CDDB.pm provides a Perl interface to the CDDB server protocols. With it, a Perl program can identify a CD based on its "table of contents" (CD-i MSF information), list its track titles, and manage track times. This information could be useful for generating CD catalogs, naming MP3 files, or even playing CDs in an automated jukebox. PUBLIC METHODS ============== new(...) Creates a CDDB server interface, returning a handle to it. This interface does not connect to the server until needed, and the CDDB protocol may require several separate connections (sometimes one per query). new accepts these parameters: Host (defaults to www.cddb.com), Port (defaults to 8880), Login (defaults to your login ID), and Debug (defaults to boolean false) parameters. `get_genres()' Takes no parameters. Returns a list of genres known by the CDDB server, or undef if there is an error. `calculate_id(...)' The CDDB protocol defines an ID as a hash of track lengths and the number of tracks, with an added checksum. The most basic information required to calculate this is the CD table of contents (the CD-i track offsets, in MSF [Minutes, Seconds, Frames] format). `calculate_id(...)' accepts TOC information as a list of strings. Each string contains four fields, separated by whitespace: 1. The track number, starting with 1. Special track numbers are 999, for the CD lead-out information; and 1000, to indicate that an error has occurred while acquiring the CD information (error tracks modify the meaning of the other fields; look below). 2. The track start, in minutes (the M in MSF). If a track starts at 01:23 and 5 frames, then this field is 1. In an error track, this field is ignored (but is expected to contain something; usually 0). 3. The track start, in seconds (the S in MSF). If a track starts at 01:23 and 5 frames, then this field is 23. In an error track, this field is ignored (but is expected to contain something; usually 0). 4. The track start, in frames (the F in MSF). If a track starts at 01:23 and 5 frames, then this field is 5. In an error track, this field contains an error message (which may contain spaces). `calculate_id(...)' returns just the ID in scalar context. In array context, it returns an array containing the following values (in the order listed here): `$cddb_id' This is the hashed CDDB ID, required for any queries involving this CD, as well as `submit_disc(...)'. `$track_numbers' This is a reference to an array containing the track numbers, padded to three characters with leading zeroes. It is provided for convenience and is not required by the CDDB. `$track_lengths' The MSF information provided to `calculate_id(...)' refers to track offsets. This is a reference to an array containing the track lengths in MM:SS format, as computed from the MSF offsets. This information is provided for convenience and is not required by the CDDB. `$track_offsets' These are absolute frame offsets as calculated by the MSF information. They are required by `get_discs(...)' and `submit_disc(...)'. `$total_seconds' This is the calculated total playing time for the CD. It is required by `get_discs(...)'. `get_discs(...)' `get_discs(...)' asks the CDDB server for all its CDs that match the given ID, track offsets list, and total seconds (combined). The CDDB performs "fuzzy" matching and may return more than one disc. `get_discs(...)' takes three parameters: `$cddb_id' This is the CDDB ID, as generated by `calculate_id(...)'. `$track_offsets' This may be in two formats. The first format is a reference to an array of absolute track offsets, similar to ones generated by `calculate_id(...)'. The second format is a string containing the track count and the absolute offsets, separated by whitespace. `$total_seconds' The total playing time for the CD, as generated by `calculate_id(...)'. `get_discs(...)' returns an array of matching discs, each of which is represented by an array reference. It returns an empty array if the query succeeded but did not match. It returns undef on error. Each disc record contains three elements, two of which can be used later on: `$genre' The genre this disc falls into, as determined by whoever submitted the disc in the first place (see `get_genres()'). `$cddb_id' The actual CDDB ID, which may be different than the one supplied to `get_discs(...)' due to fuzzy matching. `$title' The title of this disc. `get_discs_by_toc(...)' This function combines `calculate_id(...)' and `get_discs(...)' into one step. It takes the same parameters as `calculate_id(...)', and it returns the same information as `get_discs(...)'. `get_disc_details(...)' This function fetches the detailed information for a CD. It takes two parameters: the disc `$genre' and the `$cddb_id'. It returns a hash reference containing as much information as it can. The information includes data normally stored in comments. The most common entries this function returns include: `'disc length'' This is the total playing time for the disc, as recorded in the CDDB. Commonly it is in the form "somenumber seconds", but since the CDDB stores it in a comment, it could say just about anything. `'discid'' This is a rehash (get it?) of the CDDB ID, and should match the `$cddb_id' parameter to `get_disc_details(...)'. `'dtitle'' This is the disc title, again. `'offsets'' This is a reference to an array of absolute disc track offsets, in CD frames. `'ttitles'' This is a reference to an array of track titles. These are the droids you are looking for. `'processed by'' This is a comment field, identifying the CDDB server name and version. `'revision'' This is the version number for the CD record. Revisions start at 1 and are incremented for every correction. It is the responsibility of the submitter to provide a correct revision number, as sort of a sanity check. `'submitted via'' is the name and version of the software that submitted this CDDB record. The main intention is to identify records that are submitted by broken software so they can be purged or corrected. `can_submit_disc()' Returns boolean true or false. If true, CDDB.pm was able to import the MailTools it needs to send submissions. If false, it didn't, and you'll need to install at least Mail::Internet and Mail::Header (and the underlying Net::SMTP, etc.). `submit_disc(...)' `submit_disc(...)' submits a disc record to the CDDB. The CDDB accepts disc submissions through e-mail, so this function requires MailTools to operate. The rest of CDDB.pm will operate without MailTools being installed (since CDDB submissions are relatively rare), but `submit_disc(...)' will croak if MailTools are not installed. `submit_disc(...)' takes six required parameters and two optional parameters. The parameters are in pairs, like `Parameter =' $value>, and can appear in any order. Here goes: 'Genre' This is the disc genre. It must be one of the genres that the server knows (see `get_genres()'). 'Id' This is the CDDB ID, as calculated from `calculate_id(...)'. 'Artist' This is the disc artist, gleaned from the CD liner, and entered by a human. 'DiscTitle' This is the disc title, gleaned from the CD liner, and entered by a human. 'Offsets' This is a reference to an array of absolute track offsets, as provided by `calculate_id(...)'. 'TrackTitles' This is a reference to an array of track titles, gleaned from the CD liner, and entered by a human. 'From' This is the disc submitter's e-mail address. It is not required, and will default to the current user's login ID at the current machine. The CDDB will send this person a return receipt, including the full headers and body of the submitted e-mail. The default return address may not be a deliverable address, especially if CDDB.pm is being used on a dial-up machine that isn't running its own MTA. If the current machine has its own MTA, problems still may occur if the machine's Internet address changes. 'Host' This is the SMTP host to contact when sending mail. It is not required, and if omitted will default to the `SMTPHOSTS' environment variable. If `SMTPHOSTS' is not defined, it will fall back to 'mail'. If 'mail' is not a machine running an SMTP daemon, then `submit_disc(...)' will croak. PRIVATE METHODS =============== Documented as being not documented. EXAMPLES ======== Please see the cddb.t program in the t (tests) directory. It exercises every aspect of CDDB.pm. BUGS ==== There are no known bugs, but see the README for things that need to be done. CONTACT AND COPYRIGHT ===================== Copyright 1998 Rocco Caputo . All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.  File: pm.info, Node: CDDB_get, Next: CFITSIO, Prev: CDDB, Up: Module List Read the CDDB entry for an audio CD in your drive ************************************************* NAME ==== CDDB - Read the CDDB entry for an audio CD in your drive SYNOPSIS ======== use CDDB; my %config; # following variables just need to be declared if different from defaults $config{CDDB_HOST}="freedb.freedb.org"; # set cddb host $config{CDDB_PORT}=888; # set cddb port $config{CD_DEVICE}="/dev/cdrom"; # set cd device # user interaction welcome? $config{input}=1; # 1: ask user if more than one possibility # 0: no user interaction # get it on my %cd=get_cddb(\%config); unless(defined $cd{title}) { die "no cddb entry found"; } # do somthing with the results print "artist: $cd{artist}\n"; print "title: $cd{title}\n"; print "category: $cd{cat}\n"; print "cddbid: $cd{id}\n"; print "trackno: $cd{tno}\n"; my $n=1; foreach my $i ( @{$cd{track}} ) { print "track $n: $i\n"; $n++; } DESCRIPTION =========== This module/script gets the CDDB info for an audio cd. You need LINUX, a cdrom drive and an active internet connection in order to do that. LICENSE ======= This library is released under the same conditions as Perl, that is, either of the following: a) the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version. b) the Artistic License. If you use this library in a commercial enterprise, you are invited, but not required, to pay what you feel is a reasonable fee to the author, who can be contacted at armin@xos.net AUTHOR ====== Armin Obersteiner, armin@xos.net SEE ALSO ======== perl(1), .  File: pm.info, Node: CFITSIO, Next: CGI, Prev: CDDB_get, Up: Module List Perl extension for using the CFITSIO library ******************************************** NAME ==== CFITSIO - Perl extension for using the CFITSIO library SYNOPSIS ======== use CFITSIO; use CFITSIO qw( :longnames ); use CFITSIO qw( :shortnames ); use CFITSIO qw( :constants ); DESCRIPTION =========== Perl interface to William Pence's CFITSIO subroutine library. For more information on CFITSIO, see http://heasarc.gsfc.nasa.gov/fitsio. This module attempts to provide a wrapper for nearly every CFITSIO routine, while retaining as much CFITSIO behavior as possible. As such, one should be aware that it is still somewhat low-level, in the sense that handing an array which is not the correct size to a routine like `fits_write_img()' may cause SEGVs. My goal is to eventually use these routines to build a more Perl-like interface to many common tasks such as reading and writing of images and ASCII and binary tables. CFITSIO API MAPPING =================== CFITSIO.pm allows one to use either the long or short name forms of the CFITSIO routines. These work by using the exact same form of arguments as one would find in an equivalent C program. There is also an object-oriented API which uses the same function names as the long-name API, but with the leading "fits_" stripped. To get a CFITSIO "object" one would call `open_file()', `create_file()' or `create_template()': my $status = 0; my $fptr = CFITSIO::open_file($filename,CFITSIO::READONLY(),$status); $fptr->read_key_str('NAXIS1',$naxis1,undef,$status); Note that the object-oriented forms of function names are only available for those CFITSIO routines which demand a `fitsfile*' data-type as the first argument. All CFITSIO routines, with the exception of `fits_iterate_data()' and `fits_open_memfile()', are available in both long and short name forms (e.g., `fits_read_key' <=> `ffgky'), as well as all constants defined in the `fitsio.h' header file. This raises the possibility of your name space being invaded by nearly 1000 function and constant names. ********************************************************************************************************************************************************************************************************************************************************************************************************************************************************** NAME SPACE ========== All CFITSIO routines, with the exception of `fits_iterate_data()' and `fits_open_memfile()', are available in both long and short name forms (e.g., `fits_read_key' <=> `ffgky'), as well as all constants defined in the `fitsio.h' header file. This raises the possibility of your name space being invaded by nearly 1000 function and constant names. To deal with this situation, CFITSIO.pm makes use of the Exporter package support for `%EXPORT_TAGS'. You can import the long-named functions with use CFITSIO qw( :longnames ); and the short-named routines with use CFITSIO qw( :shortnames ); Constants are actually implemented as AUTOLOADed functions, so `TSTRING', for instance, would be accessed via `CFITSIO::TSTRING()'. Alternatively you can use CFITSIO qw( :constants ); which would allow you to simply say `TSTRING'. DATA STORAGE DETAILS ==================== Input Variables --------------- If a routine expects an N-dimensional array as input, and you hand it a reference to a scalar, then CFITSIO.pm simply uses the data in the scalar which the argument is referencing. Otherwise it expects the argument to be a Perl array reference whose total number of elements satisfies the input demands of the corresponding C routine. CFITSIO.pm then unpacks the array reference into a format that the C routine can understand. If your input array does not hold enough data for the C routine then a segfault is likely to occur. CFITSIO functions which take an optional NULL pointer - indicating no output in that place is desired - can instead be given an undef. In other words, the following C and Perl statements which read a keyword but ignore the comment would be roughly equivalent: fits_read_key_lng(fptr,key,&value,NULL,&status); fits_read_key_lng($fptr,$key,$value,undef,$status); Output Variables ---------------- Calling CFITSIO routines which read data from FITS files causes the output variable to be transformed into a Perl array of the appropriate dimensions. The exception to this is if one wants the output to be in the machine-native format (e.g., for use with PDL). In this case you can use the routine `PerlyUnpacking(0)'. Then all output variables will become scalars containing the appropriate data. The exception here is with routines which read arrays of strings (e.g., `fits_read_col_str()'). In this case the output is again a Perl array reference. EXAMPLES ======== Take a look at `testprog/testprog.pl' under the distribution directory. It should produce output identical to `testprog.c' which comes with the CFITSIO library. Additionally, the versions named `testprog_longnames.pl', `testprog_OO.pl' and `testprog_pdl.pl' test the long-name and object-oriented APIs, and machine-native unpacking with PDL. There is also an `examples/' directory with scripts which do the following: `image_read.pl' reads a FITS primary image and displays it using PGPLOT `image_read_pdl.pl' same as above, but uses machine-native unpacking with PDL `bintable_read_pdl.pl' reads binary table column into PDL object, makes histogram and plots it CONSIDERATIONS ============== Ensure your input arrays contain enough data The caller is responsible for ensuring that the input arrays given to CFITSIO routines are large enough to satisfy the access demands of said routines. For example, if you tell `fits_write_col()' to write a data column containing 100 elements, your Perl array should contain at least 100 elements. Segfaults abound, so beware! maxdim semantics Some CFITSIO routines take a parameter named something like 'maxdim', indicating that no more than that many elements should be placed into the output data area. An example of this would be `fits_read_tdim()'. In these cases CFITSIO.pm will automatically determine how much storage space is needed for the full amount of output possible. As a result, the arguments expected in CFITSIO.pm are slightly different than one would use in a C program, in that the 'maxdim' argument is unnecessary. Currently the routines for which this is the case are `fits_read_atblhdr()', `fits_read_btblhdr()', `fits_read_imghdr()', `fits_decode_tdim()', `fits_read_tdim()' `fits_test_expr()', `fits_get_img_parm()' and `fits_get_img_size()'. Output arrays remain as undisturbed as possible For routines like `fits_read_col()', CFITSIO.pm unpacks the output into a Perl array reference (unless `PerlyUnpacking(0)' has been called, of course). Prior to doing this, it ensures the scalar passed is a reference to an array large enough to hold the data. If the argument is an array reference which is too small, it expands the array pointed to appropriately. *But*, if the array is large enough already, the data are just unpacked into the array. The upshot: If you call `fits_read_col()', telling it to read 100 data elements, and the array you are placing the data into already has 200 elements, then after `fits_read_col()' returns your array will still have 200 elements, only the first 100 of which actually correspond to the data read by the routine. In more succinct language: @output = (0..199); fits_read_col_lng($fptr,2,1,1,100,0,\@output,$anynul,$status); # @output still has 200 elements, only first 100 are from FITS # file EXTRA COMMANDS ============== Some extra commands that use sets of CFITSIO routines are supplied to simplify some standard tasks: fits_read_header(filename) This command reads in a primary fits header (unless one is using the extended filename sytax to move to a different HDU on open) from the specified filename and returns the header as a hash reference and a status (when called in an array context) or simply a hash reference (when called in a scalar context): ($hash_ref, $status) = fits_read_header ($file); $hash_ref = fits_read_header($file); An object-oriented interface is also provided for reading headers from FITS files that have already been opened. In this case, the header read is from the current HDU. $fitsfile = CFITSIO::open_file($file); $hash_ref = $fitsfile->read_header; ($hash_ref, $status) = $fitsfile->read_header; sizeof_datatype(datatype) Returns the size of the given CFITSIO datatype constant (e.g., `CFITSIO::TSHORT()'). BUGS ==== FIXME AUTHOR ====== Pete Ratzlaff , with a great deal of code taken from Karl Glazebrook's PGPLOT module. Contributors include: Tim Jenness convenience routines Tim Conrow function implementations, bug fixes  File: pm.info, Node: CGI, Next: CGI3, Prev: CFITSIO, Up: Module List Simple Common Gateway Interface Class ************************************* NAME ==== CGI - Simple Common Gateway Interface Class SYNOPSIS ======== # CGI script that creates a fill-out form # and echoes back its values. use CGI qw/:standard/; print header, start_html('A Simple Example'), h1('A Simple Example'), start_form, "What's your name? ",textfield('name'),p, "What's the combination?", p, checkbox_group(-name=>'words', -values=>['eenie','meenie','minie','moe'], -defaults=>['eenie','minie']), p, "What's your favorite color? ", popup_menu(-name=>'color', -values=>['red','green','blue','chartreuse']),p, submit, end_form, hr; if (param()) { print "Your name is",em(param('name')),p, "The keywords are: ",em(join(", ",param('words'))),p, "Your favorite color is ",em(param('color')), hr; } ABSTRACT ======== This perl library uses perl5 objects to make it easy to create Web fill-out forms and parse their contents. This package defines CGI objects, entities that contain the values of the current query string and other state variables. Using a CGI object's methods, you can examine keywords and parameters passed to your script, and create forms whose initial values are taken from the current query (thereby preserving state information). The module provides shortcut functions that produce boilerplate HTML, reducing typing and coding errors. It also provides functionality for some of the more advanced features of CGI scripting, including support for file uploads, cookies, cascading style sheets, server push, and frames. CGI.pm also provides a simple function-oriented programming style for those who don't need its object-oriented features. The current version of CGI.pm is available at http://www.genome.wi.mit.edu/ftp/pub/software/WWW/cgi_docs.html ftp://ftp-genome.wi.mit.edu/pub/software/WWW/ DESCRIPTION =========== PROGRAMMING STYLE ----------------- There are two styles of programming with CGI.pm, an object-oriented style and a function-oriented style. In the object-oriented style you create one or more CGI objects and then use object methods to create the various elements of the page. Each CGI object starts out with the list of named parameters that were passed to your CGI script by the server. You can modify the objects, save them to a file or database and recreate them. Because each object corresponds to the "state" of the CGI script, and because each object's parameter list is independent of the others, this allows you to save the state of the script and restore it later. For example, using the object oriented style, here is how you create a simple "Hello World" HTML page: #!/usr/local/bin/perl -w use CGI; # load CGI routines $q = new CGI; # create new CGI object print $q->header, # create the HTTP header $q->start_html('hello world'), # start the HTML $q->h1('hello world'), # level 1 header $q->end_html; # end the HTML In the function-oriented style, there is one default CGI object that you rarely deal with directly. Instead you just call functions to retrieve CGI parameters, create HTML tags, manage cookies, and so on. This provides you with a cleaner programming interface, but limits you to using one CGI object at a time. The following example prints the same page, but uses the function-oriented interface. The main differences are that we now need to import a set of functions into our name space (usually the "standard" functions), and we don't need to create the CGI object. #!/usr/local/bin/perl use CGI qw/:standard/; # load standard CGI routines print header, # create the HTTP header start_html('hello world'), # start the HTML h1('hello world'), # level 1 header end_html; # end the HTML The examples in this document mainly use the object-oriented style. See HOW TO IMPORT FUNCTIONS for important information on function-oriented programming in CGI.pm CALLING CGI.PM ROUTINES ----------------------- Most CGI.pm routines accept several arguments, sometimes as many as 20 optional ones! To simplify this interface, all routines use a named argument calling style that looks like this: print $q->header(-type=>'image/gif',-expires=>'+3d'); Each argument name is preceded by a dash. Neither case nor order matters in the argument list. -type, -Type, and -TYPE are all acceptable. In fact, only the first argument needs to begin with a dash. If a dash is present in the first argument, CGI.pm assumes dashes for the subsequent ones. Several routines are commonly called with just one argument. In the case of these routines you can provide the single argument without an argument name. header() happens to be one of these routines. In this case, the single argument is the document type. print $q->header('text/html'); Other such routines are documented below. Sometimes named arguments expect a scalar, sometimes a reference to an array, and sometimes a reference to a hash. Often, you can pass any type of argument and the routine will do whatever is most appropriate. For example, the param() routine is used to set a CGI parameter to a single or a multi-valued value. The two cases are shown below: $q->param(-name=>'veggie',-value=>'tomato'); $q->param(-name=>'veggie',-value=>['tomato','tomahto','potato','potahto']); A large number of routines in CGI.pm actually aren't specifically defined in the module, but are generated automatically as needed. These are the "HTML shortcuts," routines that generate HTML tags for use in dynamically-generated pages. HTML tags have both attributes (the attribute="value" pairs within the tag itself) and contents (the part between the opening and closing pairs.) To distinguish between attributes and contents, CGI.pm uses the convention of passing HTML attributes as a hash reference as the first argument, and the contents, if any, as any subsequent arguments. It works out like this: Code Generated HTML ---- -------------- h1()

h1('some','contents');

some contents

h1({-align=>left});

h1({-align=>left},'contents');

contents

HTML tags are described in more detail later. Many newcomers to CGI.pm are puzzled by the difference between the calling conventions for the HTML shortcuts, which require curly braces around the HTML tag attributes, and the calling conventions for other routines, which manage to generate attributes without the curly brackets. Don't be confused. As a convenience the curly braces are optional in all but the HTML shortcuts. If you like, you can use curly braces when calling any routine that takes named arguments. For example: print $q->header( {-type=>'image/gif',-expires=>'+3d'} ); If you use the -w switch, you will be warned that some CGI.pm argument names conflict with built-in Perl functions. The most frequent of these is the -values argument, used to create multi-valued menus, radio button clusters and the like. To get around this warning, you have several choices: 1. Use another name for the argument, if one is available. For example, -value is an alias for -values. 2. Change the capitalization, e.g. -Values 3. Put quotes around the argument name, e.g. '-values' Many routines will do something useful with a named argument that it doesn't recognize. For example, you can produce non-standard HTTP header fields by providing them as named arguments: print $q->header(-type => 'text/html', -cost => 'Three smackers', -annoyance_level => 'high', -complaints_to => 'bit bucket'); This will produce the following nonstandard HTTP header: HTTP/1.0 200 OK Cost: Three smackers Annoyance-level: high Complaints-to: bit bucket Content-type: text/html Notice the way that underscores are translated automatically into hyphens. HTML-generating routines perform a different type of translation. This feature allows you to keep up with the rapidly changing HTTP and HTML "standards". CREATING A NEW QUERY OBJECT (OBJECT-ORIENTED STYLE): ---------------------------------------------------- $query = new CGI; This will parse the input (from both POST and GET methods) and store it into a perl5 object called $query. CREATING A NEW QUERY OBJECT FROM AN INPUT FILE ---------------------------------------------- $query = new CGI(INPUTFILE); If you provide a file handle to the new() method, it will read parameters from the file (or STDIN, or whatever). The file can be in any of the forms describing below under debugging (i.e. a series of newline delimited TAG=VALUE pairs will work). Conveniently, this type of file is created by the save() method (see below). Multiple records can be saved and restored. Perl purists will be pleased to know that this syntax accepts references to file handles, or even references to filehandle globs, which is the "official" way to pass a filehandle: $query = new CGI(\*STDIN); You can also initialize the CGI object with a FileHandle or IO::File object. If you are using the function-oriented interface and want to initialize CGI state from a file handle, the way to do this is with *restore_parameters()*. This will (re)initialize the default CGI object from the indicated file handle. open (IN,"test.in") || die; restore_parameters(IN); close IN; You can also initialize the query object from an associative array reference: $query = new CGI( {'dinosaur'=>'barney', 'song'=>'I love you', 'friends'=>[qw/Jessica George Nancy/]} ); or from a properly formatted, URL-escaped query string: $query = new CGI('dinosaur=barney&color=purple'); or from a previously existing CGI object (currently this clones the parameter list, but none of the other object-specific fields, such as autoescaping): $old_query = new CGI; $new_query = new CGI($old_query); To create an empty query, initialize it from an empty string or hash: $empty_query = new CGI(""); -or- $empty_query = new CGI({}); FETCHING A LIST OF KEYWORDS FROM THE QUERY: ------------------------------------------- @keywords = $query->keywords If the script was invoked as the result of an search, the parsed keywords can be obtained as an array using the keywords() method. FETCHING THE NAMES OF ALL THE PARAMETERS PASSED TO YOUR SCRIPT: --------------------------------------------------------------- @names = $query->param If the script was invoked with a parameter list (e.g. "name1=value1&name2=value2&name3=value3"), the param() method will return the parameter names as a list. If the script was invoked as an script and contains a string without ampersands (e.g. "value1+value2+value3") , there will be a single parameter named "keywords" containing the "+"-delimited keywords. NOTE: As of version 1.5, the array of parameter names returned will be in the same order as they were submitted by the browser. Usually this order is the same as the order in which the parameters are defined in the form (however, this isn't part of the spec, and so isn't guaranteed). FETCHING THE VALUE OR VALUES OF A SINGLE NAMED PARAMETER: --------------------------------------------------------- @values = $query->param('foo'); -or- $value = $query->param('foo'); Pass the param() method a single argument to fetch the value of the named parameter. If the parameter is multivalued (e.g. from multiple selections in a scrolling list), you can ask to receive an array. Otherwise the method will return a single value. If a value is not given in the query string, as in the queries "name1=&name2=" or "name1&name2", it will be returned as an empty string. This feature is new in 2.63. SETTING THE VALUE(S) OF A NAMED PARAMETER: ------------------------------------------ $query->param('foo','an','array','of','values'); This sets the value for the named parameter 'foo' to an array of values. This is one way to change the value of a field AFTER the script has been invoked once before. (Another way is with the -override parameter accepted by all methods that generate form elements.) param() also recognizes a named parameter style of calling described in more detail later: $query->param(-name=>'foo',-values=>['an','array','of','values']); -or- $query->param(-name=>'foo',-value=>'the value'); APPENDING ADDITIONAL VALUES TO A NAMED PARAMETER: ------------------------------------------------- $query->append(-name=>'foo',-values=>['yet','more','values']); This adds a value or list of values to the named parameter. The values are appended to the end of the parameter if it already exists. Otherwise the parameter is created. Note that this method only recognizes the named argument calling syntax. IMPORTING ALL PARAMETERS INTO A NAMESPACE: ------------------------------------------ $query->import_names('R'); This creates a series of variables in the 'R' namespace. For example, $R::foo, @R:foo. For keyword lists, a variable @R::keywords will appear. If no namespace is given, this method will assume 'Q'. WARNING: don't import anything into 'main'; this is a major security risk!!!! In older versions, this method was called import(). As of version 2.20, this name has been removed completely to avoid conflict with the built-in Perl module import operator. DELETING A PARAMETER COMPLETELY: -------------------------------- $query->delete('foo'); This completely clears a parameter. It sometimes useful for resetting parameters that you don't want passed down between script invocations. If you are using the function call interface, use "Delete()" instead to avoid conflicts with Perl's built-in delete operator. DELETING ALL PARAMETERS: ------------------------ $query->delete_all(); This clears the CGI object completely. It might be useful to ensure that all the defaults are taken when you create a fill-out form. Use Delete_all() instead if you are using the function call interface. DIRECT ACCESS TO THE PARAMETER LIST: ------------------------------------ $q->param_fetch('address')->[1] = '1313 Mockingbird Lane'; unshift @{$q->param_fetch(-name=>'address')},'George Munster'; If you need access to the parameter list in a way that isn't covered by the methods above, you can obtain a direct reference to it by calling the *param_fetch()* method with the name of the . This will return an array reference to the named parameters, which you then can manipulate in any way you like. You can also use a named argument style using the *-name* argument. FETCHING THE PARAMETER LIST AS A HASH: -------------------------------------- $params = $q->Vars; print $params->{'address'}; @foo = split("\0",$params->{'foo'}); %params = $q->Vars; use CGI ':cgi-lib'; $params = Vars; Many people want to fetch the entire parameter list as a hash in which the keys are the names of the CGI parameters, and the values are the parameters' values. The Vars() method does this. Called in a scalar context, it returns the parameter list as a tied hash reference. Changing a key changes the value of the parameter in the underlying CGI parameter list. Called in a list context, it returns the parameter list as an ordinary hash. This allows you to read the contents of the parameter list, but not to change it. When using this, the thing you must watch out for are multivalued CGI parameters. Because a hash cannot distinguish between scalar and list context, multivalued parameters will be returned as a packed string, separated by the "\0" (null) character. You must split this packed string in order to get at the individual values. This is the convention introduced long ago by Steve Brenner in his cgi-lib.pl module for Perl version 4. If you wish to use Vars() as a function, import the *:cgi-lib* set of function calls (also see the section on CGI-LIB compatibility). SAVING THE STATE OF THE SCRIPT TO A FILE: ----------------------------------------- $query->save(FILEHANDLE) This will write the current state of the form to the provided filehandle. You can read it back in by providing a filehandle to the new() method. Note that the filehandle can be a file, a pipe, or whatever! The format of the saved file is: NAME1=VALUE1 NAME1=VALUE1' NAME2=VALUE2 NAME3=VALUE3 = Both name and value are URL escaped. Multi-valued CGI parameters are represented as repeated names. A session record is delimited by a single = symbol. You can write out multiple records and read them back in with several calls to new. You can do this across several sessions by opening the file in append mode, allowing you to create primitive guest books, or to keep a history of users' queries. Here's a short example of creating multiple session records: use CGI; open (OUT,">>test.out") || die; $records = 5; foreach (0..$records) { my $q = new CGI; $q->param(-name=>'counter',-value=>$_); $q->save(OUT); } close OUT; # reopen for reading open (IN,"test.out") || die; while (!eof(IN)) { my $q = new CGI(IN); print $q->param('counter'),"\n"; } The file format used for save/restore is identical to that used by the Whitehead Genome Center's data exchange format "Boulderio", and can be manipulated and even databased using Boulderio utilities. See http://stein.cshl.org/boulder/ for further details. If you wish to use this method from the function-oriented (non-OO) interface, the exported name for this method is *save_parameters()*. RETRIEVING CGI ERRORS --------------------- Errors can occur while processing user input, particularly when processing uploaded files. When these errors occur, CGI will stop processing and return an empty parameter list. You can test for the existence and nature of errors using the *cgi_error()* function. The error messages are formatted as HTTP status codes. You can either incorporate the error text into an HTML page, or use it as the value of the HTTP status: my $error = $q->cgi_error; if ($error) { print $q->header(-status=>$error), $q->start_html('Problems'), $q->h2('Request not processed'), $q->strong($error); exit 0; } When using the function-oriented interface (see the next section), errors may only occur the first time you call param(). Be ready for this! USING THE FUNCTION-ORIENTED INTERFACE ------------------------------------- To use the function-oriented interface, you must specify which CGI.pm routines or sets of routines to import into your script's namespace. There is a small overhead associated with this importation, but it isn't much. use CGI ; The listed methods will be imported into the current package; you can call them directly without creating a CGI object first. This example shows how to import the param() and header() methods, and then use them directly: use CGI 'param','header'; print header('text/plain'); $zipcode = param('zipcode'); More frequently, you'll import common sets of functions by referring to the groups by name. All function sets are preceded with a ":" character as in ":html3" (for tags defined in the HTML 3 standard). Here is a list of the function sets you can import: :cgi Import all CGI-handling methods, such as param(), path_info() and the like. :form Import all fill-out form generating methods, such as *textfield()*. :html2 Import all methods that generate HTML 2.0 standard elements. :html3 Import all methods that generate HTML 3.0 proposed elements (such as , and ). :netscape Import all methods that generate Netscape-specific HTML extensions. :html Import all HTML-generating shortcuts (i.e. 'html2' + 'html3' + 'netscape')... :standard Import "standard" features, 'html2', 'html3', 'form' and 'cgi'. :all Import all the available methods. For the full list, see the CGI.pm code, where the variable %EXPORT_TAGS is defined. If you import a function name that is not part of CGI.pm, the module will treat it as a new HTML tag and generate the appropriate subroutine. You can then use it like any other HTML tag. This is to provide for the rapidly-evolving HTML "standard." For example, say Microsoft comes out with a new tag called (which causes the user's desktop to be flooded with a rotating gradient fill until his machine reboots). You don't need to wait for a new version of CGI.pm to start using it immediately: use CGI qw/:standard :html3 gradient/; print gradient({-start=>'red',-end=>'blue'}); Note that in the interests of execution speed CGI.pm does not use the standard *Note Exporter: Exporter, syntax for specifying load symbols. This may change in the future. If you import any of the state-maintaining CGI or form-generating methods, a default CGI object will be created and initialized automatically the first time you use any of the methods that require one to be present. This includes param(), *textfield()*, *submit()* and the like. (If you need direct access to the CGI object, you can find it in the global variable *$CGI::Q*). By importing CGI.pm methods, you can create visually elegant scripts: use CGI qw/:standard/; print header, start_html('Simple Script'), h1('Simple Script'), start_form, "What's your name? ",textfield('name'),p, "What's the combination?", checkbox_group(-name=>'words', -values=>['eenie','meenie','minie','moe'], -defaults=>['eenie','moe']),p, "What's your favorite color?", popup_menu(-name=>'color', -values=>['red','green','blue','chartreuse']),p, submit, end_form, hr,"\n"; if (param) { print "Your name is ",em(param('name')),p, "The keywords are: ",em(join(", ",param('words'))),p, "Your favorite color is ",em(param('color')),".\n"; } print end_html; PRAGMAS ------- In addition to the function sets, there are a number of pragmas that you can import. Pragmas, which are always preceded by a hyphen, change the way that CGI.pm functions in various ways. Pragmas, function sets, and individual functions can all be imported in the same use() line. For example, the following use statement imports the standard set of functions and enables debugging mode (pragma -debug): use CGI qw/:standard -debug/; The current list of pragmas is as follows: -any When you *use CGI -any*, then any method that the query object doesn't recognize will be interpreted as a new HTML tag. This allows you to support the next *ad hoc* Netscape or Microsoft HTML extension. This lets you go wild with new and unsupported tags: use CGI qw(-any); $q=new CGI; print $q->gradient({speed=>'fast',start=>'red',end=>'blue'}); Since using any causes any mistyped method name to be interpreted as an HTML tag, use it with care or not at all. -compile This causes the indicated autoloaded methods to be compiled up front, rather than deferred to later. This is useful for scripts that run for an extended period of time under FastCGI or mod_perl, and for those destined to be crunched by Malcom Beattie's Perl compiler. Use it in conjunction with the methods or method families you plan to use. use CGI qw(-compile :standard :html3); or even use CGI qw(-compile :all); Note that using the -compile pragma in this way will always have the effect of importing the compiled functions into the current namespace. If you want to compile without importing use the compile() method instead (see below). -nosticky This makes CGI.pm not generating the hidden fields .submit and .cgifields. It is very useful if you don't want to have the hidden fields appear in the querystring in a GET method. For example, a search script generated this way will have a very nice url with search parameters for bookmarking. -no_xhtml By default, CGI.pm versions 2.69 and higher emit XHTML (http://www.w3.org/TR/xhtml1/). The -no_xhtml pragma disables this feature. Thanks to Michalis Kabrianis for this feature. -nph This makes CGI.pm produce a header appropriate for an NPH (no parsed header) script. You may need to do other things as well to tell the server that the script is NPH. See the discussion of NPH scripts below. -newstyle_urls Separate the name=value pairs in CGI parameter query strings with semicolons rather than ampersands. For example: ?name=fred;age=24;favorite_color=3 Semicolon-delimited query strings are always accepted, but will not be emitted by self_url() and query_string() unless the -newstyle_urls pragma is specified. This became the default in version 2.64. -oldstyle_urls Separate the name=value pairs in CGI parameter query strings with ampersands rather than semicolons. This is no longer the default. -autoload This overrides the autoloader so that any function in your program that is not recognized is referred to CGI.pm for possible evaluation. This allows you to use all the CGI.pm functions without adding them to your symbol table, which is of concern for mod_perl users who are worried about memory consumption. Warning: when *-autoload* is in effect, you cannot use "poetry mode" (functions without the parenthesis). Use *hr()* rather than *hr*, or add something like *use subs qw/hr p header/* to the top of your script. -no_debug This turns off the command-line processing features. If you want to run a CGI.pm script from the command line to produce HTML, and you don't want it to read CGI parameters from the command line or STDIN, then use this pragma: use CGI qw(-no_debug :standard); -debug This turns on full debugging. In addition to reading CGI arguments from the command-line processing, CGI.pm will pause and try to read arguments from STDIN, producing the message "(offline mode: enter name=value pairs on standard input)" features. See the section on debugging for more details. -private_tempfiles CGI.pm can process uploaded file. Ordinarily it spools the uploaded file to a temporary directory, then deletes the file when done. However, this opens the risk of eavesdropping as described in the file upload section. Another CGI script author could peek at this data during the upload, even if it is confidential information. On Unix systems, the -private_tempfiles pragma will cause the temporary file to be unlinked as soon as it is opened and before any data is written into it, reducing, but not eliminating the risk of eavesdropping (there is still a potential race condition). To make life harder for the attacker, the program chooses tempfile names by calculating a 32 bit checksum of the incoming HTTP headers. To ensure that the temporary file cannot be read by other CGI scripts, use suEXEC or a CGI wrapper program to run your script. The temporary file is created with mode 0600 (neither world nor group readable). The temporary directory is selected using the following algorithm: 1. if the current user (e.g. "nobody") has a directory named "tmp" in its home directory, use that (Unix systems only). 2. if the environment variable TMPDIR exists, use the location indicated. 3. Otherwise try the locations /usr/tmp, /var/tmp, C:\temp, /tmp, /temp, ::Temporary Items, and \WWW_ROOT. Each of these locations is checked that it is a directory and is writable. If not, the algorithm tries the next choice. SPECIAL FORMS FOR IMPORTING HTML-TAG FUNCTIONS ---------------------------------------------- Many of the methods generate HTML tags. As described below, tag functions automatically generate both the opening and closing tags. For example: print h1('Level 1 Header'); produces

Level 1 Header

There will be some times when you want to produce the start and end tags yourself. In this case, you can use the form start_*tag_name* and end_*tag_name*, as in: print start_h1,'Level 1 Header',end_h1; With a few exceptions (described below), start_*tag_name* and end_*tag_name* functions are not generated automatically when you *use CGI*. However, you can specify the tags you want to generate *start/end* functions for by putting an asterisk in front of their name, or, alternatively, requesting either "start_*tag_name*" or "end_*tag_name*" in the import list. Example: use CGI qw/:standard *table start_ul/; In this example, the following functions are generated in addition to the standard ones: 1. start_table() (generates a
tag) 2. end_table() (generates a
tag) 3. start_ul() (generates a
    tag) 4. end_ul() (generates a
tag) GENERATING DYNAMIC DOCUMENTS ============================ Most of CGI.pm's functions deal with creating documents on the fly. Generally you will produce the HTTP header first, followed by the document itself. CGI.pm provides functions for generating HTTP headers of various types as well as for generating HTML. For creating GIF images, see the GD.pm module. Each of these functions produces a fragment of HTML or HTTP which you can print out directly so that it displays in the browser window, append to a string, or save to a file for later use. CREATING A STANDARD HTTP HEADER: -------------------------------- Normally the first thing you will do in any CGI script is print out an HTTP header. This tells the browser what type of document to expect, and gives other optional information, such as the language, expiration date, and whether to cache the document. The header can also be manipulated for special purposes, such as server push and pay per view pages. print $query->header; -or- print $query->header('image/gif'); -or- print $query->header('text/html','204 No response'); -or- print $query->header(-type=>'image/gif', -nph=>1, -status=>'402 Payment required', -expires=>'+3d', -cookie=>$cookie, -charset=>'utf-7', -attachment=>'foo.gif', -Cost=>'$2.00'); header() returns the Content-type: header. You can provide your own MIME type if you choose, otherwise it defaults to text/html. An optional second parameter specifies the status code and a human-readable message. For example, you can specify 204, "No response" to create a script that tells the browser to do nothing at all. The last example shows the named argument style for passing arguments to the CGI methods using named parameters. Recognized parameters are *-type*, *-status*, *-expires*, and *-cookie*. Any other named parameters will be stripped of their initial hyphens and turned into header fields, allowing you to specify any HTTP header you desire. Internal underscores will be turned into hyphens: print $query->header(-Content_length=>3002); Most browsers will not cache the output from CGI scripts. Every time the browser reloads the page, the script is invoked anew. You can change this behavior with the *-expires* parameter. When you specify an absolute or relative expiration interval with this parameter, some browsers and proxy servers will cache the script's output until the indicated expiration date. The following forms are all valid for the -expires field: +30s 30 seconds from now +10m ten minutes from now +1h one hour from now -1d yesterday (i.e. "ASAP!") now immediately +3M in three months +10y in ten years time Thursday, 25-Apr-1999 00:40:33 GMT at the indicated time & date The *-cookie* parameter generates a header that tells the browser to provide a "magic cookie" during all subsequent transactions with your script. Netscape cookies have a special format that includes interesting attributes such as expiration time. Use the cookie() method to create and retrieve session cookies. The *-nph* parameter, if set to a true value, will issue the correct headers to work with a NPH (no-parse-header) script. This is important to use with certain servers that expect all their scripts to be NPH. The *-charset* parameter can be used to control the character set sent to the browser. If not provided, defaults to ISO-8859-1. As a side effect, this sets the charset() method as well. The *-attachment* parameter can be used to turn the page into an attachment. Instead of displaying the page, some browsers will prompt the user to save it to disk. The value of the argument is the suggested name for the saved file. In order for this to work, you may have to set the *-type* to "application/octet-stream". GENERATING A REDIRECTION HEADER ------------------------------- print $query->redirect('http://somewhere.else/in/movie/land'); Sometimes you don't want to produce a document yourself, but simply redirect the browser elsewhere, perhaps choosing a URL based on the time of day or the identity of the user. The redirect() function redirects the browser to a different URL. If you use redirection like this, you should not print out a header as well. One hint I can offer is that relative links may not work correctly when you generate a redirection to another document on your site. This is due to a well-intentioned optimization that some servers use. The solution to this is to use the full URL (including the http: part) of the document you are redirecting to. You can also use named arguments: print $query->redirect(-uri=>'http://somewhere.else/in/movie/land', -nph=>1); The *-nph* parameter, if set to a true value, will issue the correct headers to work with a NPH (no-parse-header) script. This is important to use with certain servers, such as Microsoft Internet Explorer, which expect all their scripts to be NPH. CREATING THE HTML DOCUMENT HEADER --------------------------------- print $query->start_html(-title=>'Secrets of the Pyramids', -author=>'fred@capricorn.org', -base=>'true', -target=>'_blank', -meta=>{'keywords'=>'pharaoh secret mummy', 'copyright'=>'copyright 1996 King Tut'}, -style=>{'src'=>'/styles/style1.css'}, -BGCOLOR=>'blue'); After creating the HTTP header, most CGI scripts will start writing out an HTML document. The start_html() routine creates the top of the page, along with a lot of optional information that controls the page's appearance and behavior. This method returns a canned HTML header and the opening tag. All parameters are optional. In the named parameter form, recognized parameters are -title, -author, -base, -xbase, -dtd, -lang and -target (see below for the explanation). Any additional parameters you provide, such as the Netscape unofficial BGCOLOR attribute, are added to the tag. Additional parameters must be proceeded by a hyphen. The argument *-xbase* allows you to provide an HREF for the tag different from the current location, as in -xbase=>"http://home.mcom.com/" All relative links will be interpreted relative to this tag. The argument *-target* allows you to provide a default target frame for all the links and fill-out forms on the page. *This is a non-standard HTTP feature which only works with Netscape browsers!* See the Netscape documentation on frames for details of how to manipulate this. -target=>"answer_window" All relative links will be interpreted relative to this tag. You add arbitrary meta information to the header with the *-meta* argument. This argument expects a reference to an associative array containing name/value pairs of meta information. These will be turned into a series of header tags that look something like this: To create an HTTP-EQUIV type of tag, use *-head*, described below. The *-style* argument is used to incorporate cascading stylesheets into your code. See the section on CASCADING STYLESHEETS for more information. The *-lang* argument is used to incorporate a language attribute into the tag. The default if not specified is "en-US" for US English. For example: print $q->start_html(-lang=>'fr-CA'); You can place other arbitrary HTML elements to the section with the *-head* tag. For example, to place the rarely-used element in the head section, use this: print start_html(-head=>Link({-rel=>'next', -href=>'http://www.capricorn.com/s2.html'})); To incorporate multiple HTML elements into the section, just pass an array reference: print start_html(-head=>[ Link({-rel=>'next', -href=>'http://www.capricorn.com/s2.html'}), Link({-rel=>'previous', -href=>'http://www.capricorn.com/s1.html'}) ] ); And here's how to create an HTTP-EQUIV tag: print start_html(-head=>meta({-http_equiv => 'Content-Type', -content => 'text/html'})) JAVASCRIPTING: The *-script*, *-noScript*, *-onLoad*, *-onMouseOver*, *-onMouseOut* and *-onUnload* parameters are used to add Netscape JavaScript calls to your pages. *-script* should point to a block of text containing JavaScript function definitions. This block will be placed within a