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-package Class::Struct;
-
-## See POD after __END__
-
-use 5.005_64;
-
-use strict;
-use warnings::register;
-our(@ISA, @EXPORT, $VERSION);
-
-use Carp;
-
-require Exporter;
-@ISA = qw(Exporter);
-@EXPORT = qw(struct);
-
-$VERSION = '0.59';
-
-## Tested on 5.002 and 5.003 without class membership tests:
-my $CHECK_CLASS_MEMBERSHIP = ($] >= 5.003_95);
-
-my $print = 0;
-sub printem {
- if (@_) { $print = shift }
- else { $print++ }
-}
-
-{
- package Class::Struct::Tie_ISA;
-
- sub TIEARRAY {
- my $class = shift;
- return bless [], $class;
- }
-
- sub STORE {
- my ($self, $index, $value) = @_;
- Class::Struct::_subclass_error();
- }
-
- sub FETCH {
- my ($self, $index) = @_;
- $self->[$index];
- }
-
- sub FETCHSIZE {
- my $self = shift;
- return scalar(@$self);
- }
-
- sub DESTROY { }
-}
-
-sub import {
- my $self = shift;
-
- if ( @_ == 0 ) {
- $self->export_to_level( 1, $self, @EXPORT );
- } elsif ( @_ == 1 ) {
- # This is admittedly a little bit silly:
- # do we ever export anything else than 'struct'...?
- $self->export_to_level( 1, $self, @_ );
- } else {
- &struct;
- }
-}
-
-sub struct {
-
- # Determine parameter list structure, one of:
- # struct( class => [ element-list ])
- # struct( class => { element-list })
- # struct( element-list )
- # Latter form assumes current package name as struct name.
-
- my ($class, @decls);
- my $base_type = ref $_[1];
- if ( $base_type eq 'HASH' ) {
- $class = shift;
- @decls = %{shift()};
- _usage_error() if @_;
- }
- elsif ( $base_type eq 'ARRAY' ) {
- $class = shift;
- @decls = @{shift()};
- _usage_error() if @_;
- }
- else {
- $base_type = 'ARRAY';
- $class = (caller())[0];
- @decls = @_;
- }
-
- _usage_error() if @decls % 2 == 1;
-
- # Ensure we are not, and will not be, a subclass.
-
- my $isa = do {
- no strict 'refs';
- \@{$class . '::ISA'};
- };
- _subclass_error() if @$isa;
- tie @$isa, 'Class::Struct::Tie_ISA';
-
- # Create constructor.
-
- croak "function 'new' already defined in package $class"
- if do { no strict 'refs'; defined &{$class . "::new"} };
-
- my @methods = ();
- my %refs = ();
- my %arrays = ();
- my %hashes = ();
- my %classes = ();
- my $got_class = 0;
- my $out = '';
-
- $out = "{\n package $class;\n use Carp;\n sub new {\n";
- $out .= " my (\$class, \%init) = \@_;\n";
- $out .= " \$class = __PACKAGE__ unless \@_;\n";
-
- my $cnt = 0;
- my $idx = 0;
- my( $cmt, $name, $type, $elem );
-
- if( $base_type eq 'HASH' ){
- $out .= " my(\$r) = {};\n";
- $cmt = '';
- }
- elsif( $base_type eq 'ARRAY' ){
- $out .= " my(\$r) = [];\n";
- }
- while( $idx < @decls ){
- $name = $decls[$idx];
- $type = $decls[$idx+1];
- push( @methods, $name );
- if( $base_type eq 'HASH' ){
- $elem = "{'${class}::$name'}";
- }
- elsif( $base_type eq 'ARRAY' ){
- $elem = "[$cnt]";
- ++$cnt;
- $cmt = " # $name";
- }
- if( $type =~ /^\*(.)/ ){
- $refs{$name}++;
- $type = $1;
- }
- my $init = "defined(\$init{'$name'}) ? \$init{'$name'} :";
- if( $type eq '@' ){
- $out .= " croak 'Initializer for $name must be array reference'\n";
- $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'ARRAY';\n";
- $out .= " \$r->$elem = $init [];$cmt\n";
- $arrays{$name}++;
- }
- elsif( $type eq '%' ){
- $out .= " croak 'Initializer for $name must be hash reference'\n";
- $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'HASH';\n";
- $out .= " \$r->$elem = $init {};$cmt\n";
- $hashes{$name}++;
- }
- elsif ( $type eq '$') {
- $out .= " \$r->$elem = $init undef;$cmt\n";
- }
- elsif( $type =~ /^\w+(?:::\w+)*$/ ){
- $init = "defined(\$init{'$name'}) ? \%{\$init{'$name'}} : ()";
- $out .= " croak 'Initializer for $name must be hash reference'\n";
- $out .= " if defined(\$init{'$name'}) && ref(\$init{'$name'}) ne 'HASH';\n";
- $out .= " \$r->$elem = '${type}'->new($init);$cmt\n";
- $classes{$name} = $type;
- $got_class = 1;
- }
- else{
- croak "'$type' is not a valid struct element type";
- }
- $idx += 2;
- }
- $out .= " bless \$r, \$class;\n }\n";
-
- # Create accessor methods.
-
- my( $pre, $pst, $sel );
- $cnt = 0;
- foreach $name (@methods){
- if ( do { no strict 'refs'; defined &{$class . "::$name"} } ) {
- warnings::warnif("function '$name' already defined, overrides struct accessor method");
- }
- else {
- $pre = $pst = $cmt = $sel = '';
- if( defined $refs{$name} ){
- $pre = "\\(";
- $pst = ")";
- $cmt = " # returns ref";
- }
- $out .= " sub $name {$cmt\n my \$r = shift;\n";
- if( $base_type eq 'ARRAY' ){
- $elem = "[$cnt]";
- ++$cnt;
- }
- elsif( $base_type eq 'HASH' ){
- $elem = "{'${class}::$name'}";
- }
- if( defined $arrays{$name} ){
- $out .= " my \$i;\n";
- $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n";
- $sel = "->[\$i]";
- }
- elsif( defined $hashes{$name} ){
- $out .= " my \$i;\n";
- $out .= " \@_ ? (\$i = shift) : return \$r->$elem;\n";
- $sel = "->{\$i}";
- }
- elsif( defined $classes{$name} ){
- if ( $CHECK_CLASS_MEMBERSHIP ) {
- $out .= " croak '$name argument is wrong class' if \@_ && ! UNIVERSAL::isa(\$_[0], '$classes{$name}');\n";
- }
- }
- $out .= " croak 'Too many args to $name' if \@_ > 1;\n";
- $out .= " \@_ ? ($pre\$r->$elem$sel = shift$pst) : $pre\$r->$elem$sel$pst;\n";
- $out .= " }\n";
- }
- }
- $out .= "}\n1;\n";
-
- print $out if $print;
- my $result = eval $out;
- carp $@ if $@;
-}
-
-sub _usage_error {
- confess "struct usage error";
-}
-
-sub _subclass_error {
- croak 'struct class cannot be a subclass (@ISA not allowed)';
-}
-
-1; # for require
-
-
-__END__
-
-=head1 NAME
-
-Class::Struct - declare struct-like datatypes as Perl classes
-
-=head1 SYNOPSIS
-
- use Class::Struct;
- # declare struct, based on array:
- struct( CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ]);
- # declare struct, based on hash:
- struct( CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... });
-
- package CLASS_NAME;
- use Class::Struct;
- # declare struct, based on array, implicit class name:
- struct( ELEMENT_NAME => ELEMENT_TYPE, ... );
-
- # Declare struct at compile time
- use Class::Struct CLASS_NAME => [ ELEMENT_NAME => ELEMENT_TYPE, ... ];
- use Class::Struct CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... };
-
- package Myobj;
- use Class::Struct;
- # declare struct with four types of elements:
- struct( s => '$', a => '@', h => '%', c => 'My_Other_Class' );
-
- $obj = new Myobj; # constructor
-
- # scalar type accessor:
- $element_value = $obj->s; # element value
- $obj->s('new value'); # assign to element
-
- # array type accessor:
- $ary_ref = $obj->a; # reference to whole array
- $ary_element_value = $obj->a(2); # array element value
- $obj->a(2, 'new value'); # assign to array element
-
- # hash type accessor:
- $hash_ref = $obj->h; # reference to whole hash
- $hash_element_value = $obj->h('x'); # hash element value
- $obj->h('x', 'new value'); # assign to hash element
-
- # class type accessor:
- $element_value = $obj->c; # object reference
- $obj->c->method(...); # call method of object
- $obj->c(new My_Other_Class); # assign a new object
-
-=head1 DESCRIPTION
-
-C<Class::Struct> exports a single function, C<struct>.
-Given a list of element names and types, and optionally
-a class name, C<struct> creates a Perl 5 class that implements
-a "struct-like" data structure.
-
-The new class is given a constructor method, C<new>, for creating
-struct objects.
-
-Each element in the struct data has an accessor method, which is
-used to assign to the element and to fetch its value. The
-default accessor can be overridden by declaring a C<sub> of the
-same name in the package. (See Example 2.)
-
-Each element's type can be scalar, array, hash, or class.
-
-=head2 The C<struct()> function
-
-The C<struct> function has three forms of parameter-list.
-
- struct( CLASS_NAME => [ ELEMENT_LIST ]);
- struct( CLASS_NAME => { ELEMENT_LIST });
- struct( ELEMENT_LIST );
-
-The first and second forms explicitly identify the name of the
-class being created. The third form assumes the current package
-name as the class name.
-
-An object of a class created by the first and third forms is
-based on an array, whereas an object of a class created by the
-second form is based on a hash. The array-based forms will be
-somewhat faster and smaller; the hash-based forms are more
-flexible.
-
-The class created by C<struct> must not be a subclass of another
-class other than C<UNIVERSAL>.
-
-It can, however, be used as a superclass for other classes. To facilitate
-this, the generated constructor method uses a two-argument blessing.
-Furthermore, if the class is hash-based, the key of each element is
-prefixed with the class name (see I<Perl Cookbook>, Recipe 13.12).
-
-A function named C<new> must not be explicitly defined in a class
-created by C<struct>.
-
-The I<ELEMENT_LIST> has the form
-
- NAME => TYPE, ...
-
-Each name-type pair declares one element of the struct. Each
-element name will be defined as an accessor method unless a
-method by that name is explicitly defined; in the latter case, a
-warning is issued if the warning flag (B<-w>) is set.
-
-=head2 Class Creation at Compile Time
-
-C<Class::Struct> can create your class at compile time. The main reason
-for doing this is obvious, so your class acts like every other class in
-Perl. Creating your class at compile time will make the order of events
-similar to using any other class ( or Perl module ).
-
-There is no significant speed gain between compile time and run time
-class creation, there is just a new, more standard order of events.
-
-=head2 Element Types and Accessor Methods
-
-The four element types -- scalar, array, hash, and class -- are
-represented by strings -- C<'$'>, C<'@'>, C<'%'>, and a class name --
-optionally preceded by a C<'*'>.
-
-The accessor method provided by C<struct> for an element depends
-on the declared type of the element.
-
-=over
-
-=item Scalar (C<'$'> or C<'*$'>)
-
-The element is a scalar, and by default is initialized to C<undef>
-(but see L<Initializing with new>).
-
-The accessor's argument, if any, is assigned to the element.
-
-If the element type is C<'$'>, the value of the element (after
-assignment) is returned. If the element type is C<'*$'>, a reference
-to the element is returned.
-
-=item Array (C<'@'> or C<'*@'>)
-
-The element is an array, initialized by default to C<()>.
-
-With no argument, the accessor returns a reference to the
-element's whole array (whether or not the element was
-specified as C<'@'> or C<'*@'>).
-
-With one or two arguments, the first argument is an index
-specifying one element of the array; the second argument, if
-present, is assigned to the array element. If the element type
-is C<'@'>, the accessor returns the array element value. If the
-element type is C<'*@'>, a reference to the array element is
-returned.
-
-=item Hash (C<'%'> or C<'*%'>)
-
-The element is a hash, initialized by default to C<()>.
-
-With no argument, the accessor returns a reference to the
-element's whole hash (whether or not the element was
-specified as C<'%'> or C<'*%'>).
-
-With one or two arguments, the first argument is a key specifying
-one element of the hash; the second argument, if present, is
-assigned to the hash element. If the element type is C<'%'>, the
-accessor returns the hash element value. If the element type is
-C<'*%'>, a reference to the hash element is returned.
-
-=item Class (C<'Class_Name'> or C<'*Class_Name'>)
-
-The element's value must be a reference blessed to the named
-class or to one of its subclasses. The element is initialized to
-the result of calling the C<new> constructor of the named class.
-
-The accessor's argument, if any, is assigned to the element. The
-accessor will C<croak> if this is not an appropriate object
-reference.
-
-If the element type does not start with a C<'*'>, the accessor
-returns the element value (after assignment). If the element type
-starts with a C<'*'>, a reference to the element itself is returned.
-
-=back
-
-=head2 Initializing with C<new>
-
-C<struct> always creates a constructor called C<new>. That constructor
-may take a list of initializers for the various elements of the new
-struct.
-
-Each initializer is a pair of values: I<element name>C< =E<gt> >I<value>.
-The initializer value for a scalar element is just a scalar value. The
-initializer for an array element is an array reference. The initializer
-for a hash is a hash reference.
-
-The initializer for a class element is also a hash reference, and the
-contents of that hash are passed to the element's own constructor.
-
-See Example 3 below for an example of initialization.
-
-=head1 EXAMPLES
-
-=over
-
-=item Example 1
-
-Giving a struct element a class type that is also a struct is how
-structs are nested. Here, C<timeval> represents a time (seconds and
-microseconds), and C<rusage> has two elements, each of which is of
-type C<timeval>.
-
- use Class::Struct;
-
- struct( rusage => {
- ru_utime => timeval, # seconds
- ru_stime => timeval, # microseconds
- });
-
- struct( timeval => [
- tv_secs => '$',
- tv_usecs => '$',
- ]);
-
- # create an object:
- my $t = new rusage;
-
- # $t->ru_utime and $t->ru_stime are objects of type timeval.
- # set $t->ru_utime to 100.0 sec and $t->ru_stime to 5.0 sec.
- $t->ru_utime->tv_secs(100);
- $t->ru_utime->tv_usecs(0);
- $t->ru_stime->tv_secs(5);
- $t->ru_stime->tv_usecs(0);
-
-=item Example 2
-
-An accessor function can be redefined in order to provide
-additional checking of values, etc. Here, we want the C<count>
-element always to be nonnegative, so we redefine the C<count>
-accessor accordingly.
-
- package MyObj;
- use Class::Struct;
-
- # declare the struct
- struct ( 'MyObj', { count => '$', stuff => '%' } );
-
- # override the default accessor method for 'count'
- sub count {
- my $self = shift;
- if ( @_ ) {
- die 'count must be nonnegative' if $_[0] < 0;
- $self->{'count'} = shift;
- warn "Too many args to count" if @_;
- }
- return $self->{'count'};
- }
-
- package main;
- $x = new MyObj;
- print "\$x->count(5) = ", $x->count(5), "\n";
- # prints '$x->count(5) = 5'
-
- print "\$x->count = ", $x->count, "\n";
- # prints '$x->count = 5'
-
- print "\$x->count(-5) = ", $x->count(-5), "\n";
- # dies due to negative argument!
-
-=item Example 3
-
-The constructor of a generated class can be passed a list
-of I<element>=>I<value> pairs, with which to initialize the struct.
-If no initializer is specified for a particular element, its default
-initialization is performed instead. Initializers for non-existent
-elements are silently ignored.
-
-Note that the initializer for a nested struct is specified
-as an anonymous hash of initializers, which is passed on to the nested
-struct's constructor.
-
- use Class::Struct;
-
- struct Breed =>
- {
- name => '$',
- cross => '$',
- };
-
- struct Cat =>
- [
- name => '$',
- kittens => '@',
- markings => '%',
- breed => 'Breed',
- ];
-
-
- my $cat = Cat->new( name => 'Socks',
- kittens => ['Monica', 'Kenneth'],
- markings => { socks=>1, blaze=>"white" },
- breed => { name=>'short-hair', cross=>1 },
- );
-
- print "Once a cat called ", $cat->name, "\n";
- print "(which was a ", $cat->breed->name, ")\n";
- print "had two kittens: ", join(' and ', @{$cat->kittens}), "\n";
-
-=back
-
-=head1 Author and Modification History
-
-Modified by Casey Tweten, 2000-11-08, v0.59.
-
- Added the ability for compile time class creation.
-
-Modified by Damian Conway, 1999-03-05, v0.58.
-
- Added handling of hash-like arg list to class ctor.
-
- Changed to two-argument blessing in ctor to support
- derivation from created classes.
-
- Added classname prefixes to keys in hash-based classes
- (refer to "Perl Cookbook", Recipe 13.12 for rationale).
-
- Corrected behaviour of accessors for '*@' and '*%' struct
- elements. Package now implements documented behaviour when
- returning a reference to an entire hash or array element.
- Previously these were returned as a reference to a reference
- to the element.
-
-Renamed to C<Class::Struct> and modified by Jim Miner, 1997-04-02.
-
- members() function removed.
- Documentation corrected and extended.
- Use of struct() in a subclass prohibited.
- User definition of accessor allowed.
- Treatment of '*' in element types corrected.
- Treatment of classes as element types corrected.
- Class name to struct() made optional.
- Diagnostic checks added.
-
-Originally C<Class::Template> by Dean Roehrich.
-
- # Template.pm --- struct/member template builder
- # 12mar95
- # Dean Roehrich
- #
- # changes/bugs fixed since 28nov94 version:
- # - podified
- # changes/bugs fixed since 21nov94 version:
- # - Fixed examples.
- # changes/bugs fixed since 02sep94 version:
- # - Moved to Class::Template.
- # changes/bugs fixed since 20feb94 version:
- # - Updated to be a more proper module.
- # - Added "use strict".
- # - Bug in build_methods, was using @var when @$var needed.
- # - Now using my() rather than local().
- #
- # Uses perl5 classes to create nested data types.
- # This is offered as one implementation of Tom Christiansen's "structs.pl"
- # idea.
-
-=cut
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