=head1 VERSION
-Version 0.30
+Version 0.31
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.30';
+ $VERSION = '0.31';
}
=head1 SYNOPSIS
- use Variable::Magic qw/wizard cast dispell/;
+ use Variable::Magic qw/wizard cast VMG_OP_INFO_NAME/;
- my $wiz = wizard set => sub { print STDERR "now set to ${$_[0]}!\n" };
- my $a = 1;
- cast $a, $wiz;
- $a = 2; # "now set to 2!"
- dispell $a, $wiz;
- $a = 3 # (nothing)
+ { # A variable tracer
+ my $wiz = wizard set => sub { print "now set to ${$_[0]}!\n" },
+ free => sub { print "destroyed!\n" };
+
+ my $a = 1;
+ cast $a, $wiz;
+ $a = 2; # "now set to 2!"
+ } # "destroyed!"
+
+ { # A hash with a default value
+ my $wiz = wizard data => sub { $_[1] },
+ fetch => sub { $_[2] = $_[1] unless exists $_[0]->{$_[2]}; () },
+ store => sub { print "key $_[2] stored in $_[-1]\n" },
+ copy_key => 1,
+ op_info => VMG_OP_INFO_NAME;
+
+ my %h = (_default => 0, apple => 2);
+ cast %h, $wiz, '_default';
+ print $h{banana}, "\n"; # "0", because the 'banana' key doesn't exist in %h
+ $h{pear} = 1; # "key pear stored in helem"
+ }
=head1 DESCRIPTION
To prevent any clash between different magics defined with this module, an unique numerical signature is attached to each kind of magic (i.e. each set of callbacks for magic operations).
-=head1 PERL MAGIC HISTORY
-
-The places where magic is invoked have changed a bit through perl history.
-Here's a little list of the most recent ones.
-
-=over 4
-
-=item *
-
-B<5.6.x>
-
-I<p14416> : 'copy' and 'dup' magic.
-
-=item *
-
-B<5.8.9>
-
-I<p28160> : Integration of I<p25854> (see below).
-
-I<p32542> : Integration of I<p31473> (see below).
-
-=item *
-
-B<5.9.3>
-
-I<p25854> : 'len' magic is no longer called when pushing an element into a magic array.
-
-I<p26569> : 'local' magic.
-
-=item *
-
-B<5.9.5>
-
-I<p31064> : Meaningful 'uvar' magic.
-
-I<p31473> : 'clear' magic wasn't invoked when undefining an array.
-The bug is fixed as of this version.
-
-=item *
-
-B<5.10.0>
-
-Since C<PERL_MAGIC_uvar> is uppercased, C<hv_magic_check()> triggers 'copy' magic on hash stores for (non-tied) hashes that also have 'uvar' magic.
-
-=item *
-
-B<5.11.x>
-
-I<p32969> : 'len' magic is no longer invoked when calling C<length> with a magical scalar.
-
-I<p34908> : 'len' magic is no longer called when pushing / unshifting an element into a magical array in void context.
-The C<push> part was already covered by I<p25854>.
-
-=back
-
-=head1 CONSTANTS
-
-=head2 C<SIG_MIN>
-
-The minimum integer used as a signature for user-defined magic.
-
-=head2 C<SIG_MAX>
-
-The maximum integer used as a signature for user-defined magic.
-
-=head2 C<SIG_NBR>
-
- SIG_NBR = SIG_MAX - SIG_MIN + 1
-
-=head2 C<MGf_COPY>
-
-Evaluates to true iff the 'copy' magic is available.
-
-=head2 C<MGf_DUP>
-
-Evaluates to true iff the 'dup' magic is available.
-
-=head2 C<MGf_LOCAL>
-
-Evaluates to true iff the 'local' magic is available.
-
-=head2 C<VMG_UVAR>
-
-When this constant is true, you can use the C<fetch,store,exists,delete> callbacks on hashes.
-
-=head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN>
-
-True for perls that don't call 'len' magic when you push an element in a magical array.
-
-=head2 C<VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID>
-
-True for perls that don't call 'len' magic when you unshift in void context an element in a magical array.
-
-=head2 C<VMG_COMPAT_ARRAY_UNDEF_CLEAR>
-
-True for perls that call 'clear' magic when undefining magical arrays.
-
-=head2 C<VMG_COMPAT_SCALAR_LENGTH_NOLEN>
-
-True for perls that don't call 'len' magic when taking the C<length> of a magical scalar.
-
-=head2 C<VMG_PERL_PATCHLEVEL>
-
-The perl patchlevel this module was built with, or C<0> for non-debugging perls.
-
-=head2 C<VMG_THREADSAFE>
-
-True iff this module could have been built with thread-safety features enabled.
-
-=head2 C<VMG_OP_INFO_NAME>
-
-Value to pass with C<op_info> to get the current op name in the magic callbacks.
-
-=head2 C<VMG_OP_INFO_OBJECT>
-
-Value to pass with C<op_info> to get a C<B::OP> object representing the current op in the magic callbacks.
-
=head1 FUNCTIONS
=cut
set => sub { print STDERR "set to ${$_[0]}\n" },
free => sub { print STDERR "${$_[0]} was deleted\n" }
+Note that C<free> callbacks are I<never> called during global destruction, as there's no way to ensure that the wizard and the C<free> coderef weren't destroyed before the scalar.
+
=cut
sub wizard {
If you want to overcome the possible deletion of the C<'TZ'> entry, you have no choice but to rely on C<store> uvar magic.
+C<cast> can be called from any magical callback, and in particular from C<data>.
+This allows you to recursively cast magic on datastructures :
+
+ my $wiz;
+ $wiz = wizard
+ data => sub {
+ my ($var, $depth) = @_;
+ $depth ||= 0;
+ my $r = ref $var;
+ if ($r eq 'ARRAY') {
+ &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for @$var;
+ } elsif ($r eq 'HASH') {
+ &cast((ref() ? $_ : \$_), $wiz, $depth + 1) for values %$var;
+ }
+ return $depth;
+ },
+ free => sub {
+ my ($var, $depth) = @_;
+ my $r = ref $var;
+ print "free $r at depth $depth\n";
+ ();
+ };
+
+ {
+ my %h = (
+ a => [ 1, 2 ],
+ b => { c => 3 }
+ );
+ cast %h, $wiz;
+ }
+
+When C<%h> goes out of scope, this will print something among the lines of :
+
+ free HASH at depth 0
+ free HASH at depth 1
+ free SCALAR at depth 2
+ free ARRAY at depth 1
+ free SCALAR at depth 3
+ free SCALAR at depth 3
+
+Of course, this example does nothing with the values that are added after the C<cast>.
+
=head2 C<getdata>
getdata [$@%&*]var, [$wiz|$sig]
# Dispell now. If $wiz isn't a signature, undef can't be returned.
die 'no such magic or error' unless dispell $x, $wiz;
+=head1 CONSTANTS
+
+=head2 C<SIG_MIN>
+
+The minimum integer used as a signature for user-defined magic.
+
+=head2 C<SIG_MAX>
+
+The maximum integer used as a signature for user-defined magic.
+
+=head2 C<SIG_NBR>
+
+ SIG_NBR = SIG_MAX - SIG_MIN + 1
+
+=head2 C<MGf_COPY>
+
+Evaluates to true iff the 'copy' magic is available.
+
+=head2 C<MGf_DUP>
+
+Evaluates to true iff the 'dup' magic is available.
+
+=head2 C<MGf_LOCAL>
+
+Evaluates to true iff the 'local' magic is available.
+
+=head2 C<VMG_UVAR>
+
+When this constant is true, you can use the C<fetch,store,exists,delete> callbacks on hashes.
+
+=head2 C<VMG_COMPAT_ARRAY_PUSH_NOLEN>
+
+True for perls that don't call 'len' magic when you push an element in a magical array.
+
+=head2 C<VMG_COMPAT_ARRAY_UNSHIFT_NOLEN_VOID>
+
+True for perls that don't call 'len' magic when you unshift in void context an element in a magical array.
+
+=head2 C<VMG_COMPAT_ARRAY_UNDEF_CLEAR>
+
+True for perls that call 'clear' magic when undefining magical arrays.
+
+=head2 C<VMG_COMPAT_SCALAR_LENGTH_NOLEN>
+
+True for perls that don't call 'len' magic when taking the C<length> of a magical scalar.
+
+=head2 C<VMG_PERL_PATCHLEVEL>
+
+The perl patchlevel this module was built with, or C<0> for non-debugging perls.
+
+=head2 C<VMG_THREADSAFE>
+
+True iff this module could have been built with thread-safety features enabled.
+
+=head2 C<VMG_OP_INFO_NAME>
+
+Value to pass with C<op_info> to get the current op name in the magic callbacks.
+
+=head2 C<VMG_OP_INFO_OBJECT>
+
+Value to pass with C<op_info> to get a C<B::OP> object representing the current op in the magic callbacks.
+
+=head1 PERL MAGIC HISTORY
+
+The places where magic is invoked have changed a bit through perl history.
+Here's a little list of the most recent ones.
+
+=over 4
+
+=item *
+
+B<5.6.x>
+
+I<p14416> : 'copy' and 'dup' magic.
+
+=item *
+
+B<5.8.9>
+
+I<p28160> : Integration of I<p25854> (see below).
+
+I<p32542> : Integration of I<p31473> (see below).
+
+=item *
+
+B<5.9.3>
+
+I<p25854> : 'len' magic is no longer called when pushing an element into a magic array.
+
+I<p26569> : 'local' magic.
+
+=item *
+
+B<5.9.5>
+
+I<p31064> : Meaningful 'uvar' magic.
+
+I<p31473> : 'clear' magic wasn't invoked when undefining an array.
+The bug is fixed as of this version.
+
+=item *
+
+B<5.10.0>
+
+Since C<PERL_MAGIC_uvar> is uppercased, C<hv_magic_check()> triggers 'copy' magic on hash stores for (non-tied) hashes that also have 'uvar' magic.
+
+=item *
+
+B<5.11.x>
+
+I<p32969> : 'len' magic is no longer invoked when calling C<length> with a magical scalar.
+
+I<p34908> : 'len' magic is no longer called when pushing / unshifting an element into a magical array in void context.
+The C<push> part was already covered by I<p25854>.
+
+=back
+
=head1 EXPORT
The functions L</wizard>, L</gensig>, L</getsig>, L</cast>, L</getdata> and L</dispell> are only exported on request.
All of them are exported by the tags C<':funcs'> and C<':all'>.
-The constants L</SIG_MIN>, L</SIG_MAX>, L</SIG_NBR>, L</MGf_COPY>, L</MGf_DUP>, L</MGf_LOCAL> and L</VMG_UVAR> are also only exported on request.
-They are all exported by the tags C<':consts'> and C<':all'>.
+All the constants are also only exported on request, either individually or by the tags C<':consts'> and C<':all'>.
=cut
projects / perl / modules / Variable-Magic.git / blobdiff