X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=README;h=8ad082d71ece64f21a391b9f0eab95cb35585bb8;hb=37da09a2cefd59ff5d24c60c77a14a3fcfb1e83e;hp=944ed1936a9cce0c05590278aa8b6e9bc291d7b6;hpb=91aec4cfae75e61ff8eeb79448501a8739b0d240;p=perl%2Fmodules%2FVariable-Magic.git diff --git a/README b/README index 944ed19..8ad082d 100644 --- a/README +++ b/README @@ -2,7 +2,7 @@ NAME Variable::Magic - Associate user-defined magic to variables from Perl. VERSION - Version 0.15 + Version 0.25 SYNOPSIS use Variable::Magic qw/wizard cast dispell/; @@ -16,50 +16,74 @@ SYNOPSIS DESCRIPTION Magic is Perl way of enhancing objects. This mechanism let the user add - extra data to any variable and overload syntaxical operations (such as + 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. + Magic differs from tieing and overloading in several ways : + + * Magic isn't copied on assignation (as for blessed references) : you + attach it to variables, not values. + + * It doesn't replace the original semantics : magic callbacks trigger + before the original action take place, and can't prevent it to + happen. + + * It's mostly invisible at the Perl level : magical and non-magical + variables cannot be distinguished with "ref", "reftype" or another + trick. + + * It's notably faster, since perl's way of handling magic is lighter + by nature, and there's no need for any method resolution. + The operations that can be overloaded are : - "get" + * "get" + This magic is invoked when the variable is evaluated (does not include array/hash subscripts and slices). - "set" + * "set" + This one is triggered each time the value of the variable changes (includes array/hash subscripts and slices). - "len" + * "len" + This magic is a little special : it is called when the 'size' or the 'length' of the variable has to be known by Perl. Typically, it's the magic involved when an array is evaluated in scalar context, but also on array assignation and loops ("for", "map" or "grep"). The callback has then to return the length as an integer. - "clear" + * "clear" + This magic is invoked when the variable is reset, such as when an array is emptied. Please note that this is different from undefining the variable, even though the magic is called when the clearing is a result of the undefine (e.g. for an array, but actually a bug prevent it to work before perl 5.9.5 - see the history). - "free" + * "free" + This one can be considered as an object destructor. It happens when the variable goes out of scope (with the exception of global scope), but not when it is undefined. - "copy" + * "copy" + This magic only applies to tied arrays and hashes. It fires when you try to access or change their elements. It is available on your perl iff "MGf_COPY" is true. - "dup" + * "dup" + Invoked when the variable is cloned across threads. Currently not available. - "local" + * "local" + When this magic is set on a variable, all subsequent localizations of the variable will trigger the callback. It is available on your perl iff "MGf_LOCAL" is true. @@ -67,16 +91,20 @@ DESCRIPTION The following actions only apply to hashes and are available iff "VMG_UVAR" is true. They are referred to as "uvar" magics. - "fetch" + * "fetch" + This magic happens each time an element is fetched from the hash. - "store" + * "store" + This one is called when an element is stored into the hash. - "exists" + * "exists" + This magic fires when a key is tested for existence in the hash. - "delete" + * "delete" + This last one triggers when a key is deleted in the hash, regardless of whether the key actually exists in it. @@ -91,27 +119,34 @@ 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. - 5.6.x - *p14416* : 'copy' and 'dup' magic. + * 5.6.x - 5.9.3 - *p25854* : 'len' magic is no longer called when pushing an element into - a magic array. - *p26569* : 'local' magic. + *p14416* : 'copy' and 'dup' magic. - 5.9.5 - *p31064* : Meaningful 'uvar' magic. - *p31473* : 'clear' magic wasn't invoked when undefining an array. The - bug is fixed as of this version. + * 5.9.3 - 5.10.0 - Since "PERL_MAGIC_uvar" is uppercased, "hv_magic_check()" triggers - 'copy' magic on hash stores for (non-tied) hashes that also have 'uvar' - magic. + *p25854* : 'len' magic is no longer called when pushing an element + into a magic array. - 5.11.x - *p32969* : 'len' magic is no longer invoked when calling "length" with a - magical scalar. + *p26569* : 'local' magic. + + * 5.9.5 + + *p31064* : Meaningful 'uvar' magic. + + *p31473* : 'clear' magic wasn't invoked when undefining an array. + The bug is fixed as of this version. + + * 5.10.0 + + Since "PERL_MAGIC_uvar" is uppercased, "hv_magic_check()" triggers + 'copy' magic on hash stores for (non-tied) hashes that also have + 'uvar' magic. + + * 5.11.x + + *p32969* : 'len' magic is no longer invoked when calling "length" + with a magical scalar. CONSTANTS "SIG_MIN" @@ -147,6 +182,14 @@ CONSTANTS True for perls that don't call 'len' magic when taking the "length" of a magical scalar. + "VMG_PERL_PATCHLEVEL" + The perl patchlevel this module was built with, or 0 for non-debugging + perls. + + "VMG_THREADSAFE" + True iff this module could have been built with thread-safety features + enabled. + FUNCTIONS "wizard" wizard sig => ..., @@ -167,20 +210,23 @@ FUNCTIONS information. It takes a list of keys / values as argument, whose keys can be : - "sig" + * "sig" + The numerical signature. If not specified or undefined, a random signature is generated. If the signature matches an already defined magic, then the existant magic object is returned. - "data" + * "data" + A code reference to a private data constructor. It is called each time this magic is cast on a variable, and the scalar returned is used as private data storage for it. $_[0] is a reference to the magic object and @_[1 .. @_-1] are all extra arguments that were passed to "cast". - "get", "set", "len", "clear", "free", "copy", "local", "fetch", "store", - "exists" and "delete" + * "get", "set", "len", "clear", "free", "copy", "local", "fetch", + "store", "exists" and "delete" + Code references to corresponding magic callbacks. You don't have to specify all of them : the magic associated with undefined entries simply won't be hooked. In those callbacks, $_[0] is always a @@ -284,6 +330,8 @@ DEPENDENCIES Glob tests need Symbol (standard since perl 5.002). + Threads tests need threads and threads::shared. + SEE ALSO perlguts and perlapi for internal information about magic. @@ -292,8 +340,7 @@ SEE ALSO AUTHOR Vincent Pit, "", . - You can contact me by mail or on #perl @ FreeNode (vincent or - Prof_Vince). + You can contact me by mail or on "irc.perl.org" (vincent). BUGS Please report any bugs or feature requests to "bug-variable-magic at