X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FVariable%2FMagic.pm;h=50ada382a335532c33bbffb9562d3f1eb117eae7;hb=4dd0e1a154147b46684ab875e7d052296b8ac629;hp=27e482c33c19639b6204c9b87317aa0b9fc740f3;hpb=4928f1e28fe3594d29e214901ac76c7975eea7e0;p=perl%2Fmodules%2FVariable-Magic.git

diff --git a/lib/Variable/Magic.pm b/lib/Variable/Magic.pm
index 27e482c..50ada38 100644
--- a/lib/Variable/Magic.pm
+++ b/lib/Variable/Magic.pm
@@ -13,13 +13,13 @@ Variable::Magic - Associate user-defined magic to variables from Perl.
 
 =head1 VERSION
 
-Version 0.29
+Version 0.30
 
 =cut
 
 our $VERSION;
 BEGIN {
- $VERSION = '0.29';
+ $VERSION = '0.30';
 }
 
 =head1 SYNOPSIS
@@ -36,28 +36,49 @@ BEGIN {
 =head1 DESCRIPTION
 
 Magic is Perl way of enhancing objects.
-This mechanism let the user add extra data to any variable and hook syntaxical operations (such as access, assignation or destruction) that can be applied to it.
-With this module, you can add your own magic to any variable without the pain of the C API.
+This mechanism lets the user add extra data to any variable and hook syntaxical operations (such as access, assignation or destruction) that can be applied to it.
+With this module, you can add your own magic to any variable without having to write a single line of XS.
 
-Magic differs from tieing and overloading in several ways :
+You'll realize that these magic variables look a lot like tied variables.
+It's not surprising, as tied variables are implemented as a special kind of magic, just like any 'irregular' Perl variable : scalars like C<$!>, C<$(> or C<$^W>, the C<%ENV> and C<%SIG> hashes, the C<@ISA> array,  C<vec()> and C<substr()> lvalues, L<thread::shared> variables...
+They all share the same underlying C API, and this module gives you direct access to it.
+
+Still, the magic made available by this module differs from tieing and overloading in several ways :
 
 =over 4
 
 =item *
 
-Magic isn't copied on assignation (as for blessed references) : you attach it to variables, not values.
+It isn't copied on assignation.
+
+You attach it to variables, not values (as for blessed references).
 
 =item *
 
-It doesn't replace the original semantics : magic callbacks trigger before the original action take place, and can't prevent it to happen.
+It doesn't replace the original semantics.
+
+Magic callbacks trigger before the original action take place, and can't prevent it to happen.
+This makes catching individual events easier than with C<tie>, where you have to provide fallbacks methods for all actions by usually inheriting from the correct C<Tie::Std*> class and overriding individual methods in your own class.
 
 =item *
 
-It's mostly invisible at the Perl level : magical and non-magical variables cannot be distinguished with C<ref>, C<reftype> or another trick.
+It's type-agnostic.
+
+The same magic can be applied on scalars, arrays, hashes, subs or globs.
+But the same hook (see below for a list) may trigger differently depending on the the type of the variable.
 
 =item *
 
-It's notably faster, since perl's way of handling magic is lighter by nature, and there's no need for any method resolution.
+It's mostly invisible at the Perl level.
+
+Magical and non-magical variables cannot be distinguished with C<ref>, C<tied> or another trick.
+
+=item *
+
+It's notably faster.
+
+Mainly because perl's way of handling magic is lighter by nature, and because there's no need for any method resolution.
+Also, since you don't have to reimplement all the variable semantics, you only pay for what you actually use.
 
 =back
 
@@ -423,6 +444,15 @@ If the variable isn't a hash, any C<uvar> callback of the wizard is safely ignor
     my $x;
     die 'error' unless cast $x, $wiz;
 
+The C<var> argument can be an array or hash value.
+Magic for those behaves like for any other scalar, except that it is dispelled when the entry is deleted from the container.
+For example, if you want to call C<POSIX::tzset> each time the C<'TZ'> environment variable is changed in C<%ENV>, you can use :
+
+    use POSIX;
+    cast $ENV{TZ}, wizard set => sub { POSIX::tzset(); () };
+
+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.
+
 =head2 C<getdata>
 
     getdata [$@%&*]var, [$wiz|$sig]
@@ -470,8 +500,6 @@ our %EXPORT_TAGS    = (
 our @EXPORT_OK      = map { @$_ } values %EXPORT_TAGS;
 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
 
-END { _cleanup() }
-
 =head1 CAVEATS
 
 If you store a magic object in the private data slot, the magic won't be accessible by L</getdata> since it's not copied by assignation.