Variable::Magic - Associate user-defined magic to variables from Perl.
VERSION
- Version 0.50
+ Version 0.53
SYNOPSIS
use Variable::Magic qw<wizard cast VMG_OP_INFO_NAME>;
the correct "Tie::Std*" class and overriding individual methods in
your own class.
+ * Magic is multivalued.
+
+ You can safely apply different kinds of magics to the same variable,
+ and each of them will be invoked successively.
+
* Magic is 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.
+ differently depending on the type of the variable.
- * Magic is invisible at the Perl level.
+ * Magic is invisible at Perl level.
Magical and non-magical variables cannot be distinguished with
"ref", "tied" or another trick.
* *len*
- This magic only applies to scalars and arrays, and is triggered when
- the 'size' or the 'length' of the variable has to be known by Perl.
- This is typically the magic involved when an array is evaluated in
- scalar context, but also on array assignment and loops ("for", "map"
- or "grep"). The length is returned from the callback as an integer.
+ This magic only applies to arrays (though it used to also apply to
+ scalars), and is triggered when the 'size' or the 'length' of the
+ variable has to be known by Perl. This is typically the magic
+ involved when an array is evaluated in scalar context, but also on
+ array assignment and loops ("for", "map" or "grep"). The length is
+ returned from the callback as an integer.
+
+ Starting from perl 5.12, this magic is no longer called by the
+ "length" keyword, and starting from perl 5.17.4 it is also no longer
+ called for scalars in any situation, making this magic only
+ meaningful on arrays. You can use the constants
+ "VMG_COMPAT_SCALAR_LENGTH_NOLEN" and "VMG_COMPAT_SCALAR_NOLEN" to
+ see if this magic is available for scalars or not.
* *clear*
* *free*
- This magic is called when an object is destroyed as the result of
- the variable going out of scope (but not when the variable is
- undefined).
+ This magic is called when a variable is destroyed as the result of
+ going out of scope (but not when it is undefined). It behaves
+ roughly like Perl object destructors (i.e. "DESTROY" methods),
+ except that exceptions thrown from inside a *free* callback will
+ always be propagated to the surrounding code.
* *copy*
True for perls that don't call *len* magic when taking the "length" of a
magical scalar.
+ "VMG_COMPAT_SCALAR_NOLEN"
+ True for perls that don't call *len* magic on scalars. Implies
+ "VMG_COMPAT_SCALAR_LENGTH_NOLEN".
+
"VMG_COMPAT_ARRAY_PUSH_NOLEN"
True for perls that don't call *len* magic when you push an element in a
magical array. Starting from perl 5.11.0, this only refers to pushes in
A C compiler. This module may happen to build with a C++ compiler as
well, but don't rely on it, as no guarantee is made in this regard.
- Carp (core since perl 5), XSLoader (since 5.006).
+ Carp (core since perl 5), XSLoader (since 5.6.0).
Copy tests need Tie::Array (core since perl 5.005) and Tie::Hash (since
- 5.002). Some uvar tests need Hash::Util::FieldHash (since 5.009004).
- Glob tests need Symbol (since 5.002). Threads tests need threads and
- threads::shared (both since 5.007003).
+ 5.002). Some uvar tests need Hash::Util::FieldHash (since 5.9.4). Glob
+ tests need Symbol (since 5.002). Threads tests need threads and
+ threads::shared (both since 5.7.3).
SEE ALSO
perlguts and perlapi for internal information about magic.
<http://www.profvince.com/perl/cover/Variable-Magic>.
COPYRIGHT & LICENSE
- Copyright 2007,2008,2009,2010,2011,2012 Vincent Pit, all rights
+ Copyright 2007,2008,2009,2010,2011,2012,2013 Vincent Pit, all rights
reserved.
This program is free software; you can redistribute it and/or modify it
projects / perl / modules / Variable-Magic.git / blobdiff