X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=README;h=7e89615a996e668ab39c2fa058d18332108a96c8;hb=91932481de315250b46c30c8251490ed822ed40d;hp=0a385c122a261c002f85abcb51495db85afcf3d1;hpb=763ba8093427f3668368fa885741618ac6289d41;p=perl%2Fmodules%2FVariable-Magic.git diff --git a/README b/README index 0a385c1..7e89615 100644 --- a/README +++ b/README @@ -2,7 +2,7 @@ NAME Variable::Magic - Associate user-defined magic to variables from Perl. VERSION - Version 0.08 + Version 0.20 SYNOPSIS use Variable::Magic qw/wizard cast dispell/; @@ -23,60 +23,72 @@ DESCRIPTION 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. - The following actions only applies to hashes and are available iff + 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. @@ -91,18 +103,34 @@ 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 + + *p14416* : 'copy' and 'dup' magic. + + * 5.9.3 + + *p25854* : 'len' magic is no longer called when pushing an element + into a magic array. + + *p26569* : 'local' magic. + + * 5.9.5 - 5.9.3 - 'len' magic is no longer called when pushing an element into a magic - array. - *p26569* : 'local' magic. + *p31064* : Meaningful 'uvar' 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. + *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" @@ -127,6 +155,25 @@ CONSTANTS When this constant is true, you can use the "fetch,store,exists,delete" callbacks on hashes. + "VMG_COMPAT_ARRAY_PUSH_NOLEN" + True for perls that don't call 'len' magic when you push an element in a + magical array. + + "VMG_COMPAT_ARRAY_UNDEF_CLEAR" + True for perls that call 'clear' magic when undefining magical arrays. + + "VMG_COMPAT_SCALAR_LENGTH_NOLEN" + 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 => ..., @@ -136,7 +183,7 @@ FUNCTIONS len => sub { my ($ref, $data, $len) = @_; ... ; return $newlen; }, clear => sub { my ($ref, $data) = @_; ... }, free => sub { my ($ref, $data) = @_, ... }, - copy => sub { my ($ref, $data, $elt) = @_; ... }, + copy => sub { my ($ref, $data, $key, $elt) = @_; ... }, local => sub { my ($ref, $data) = @_; ... }, fetch => sub { my ($ref, $data, $key) = @_; ... }, store => sub { my ($ref, $data, $key) = @_; ... }, @@ -147,29 +194,34 @@ 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 reference to the magic object and $_[1] is always the private data (or "undef" when no private data constructor was supplied). In the special case of "len" magic and when the variable is an array, $_[2] - contains its normal length. "copy" magic receives the current - element (i.e. the value) in $_[2]. $_[2] is also the current key in - "fetch", "store", "exists" and "delete" callbacks. + contains its normal length. $_[2] is the current key in "copy", + "fetch", "store", "exists" and "delete" callbacks, although for + "copy" it may just be a copy of the actual key so it's useless to + (for example) cast magic on it. "copy" magic also receives the + current element (i.e. the value) in $_[3]. # A simple scalar tracer my $wiz = wizard get => sub { print STDERR "got ${$_[0]}\n" }, @@ -201,7 +253,8 @@ FUNCTIONS magic is already present, 0 on error, and "undef" when no magic corresponds to the given signature (in case $sig was supplied). All extra arguments specified after $wiz are passed to the private data - constructor. + constructor. If the variable isn't a hash, any "uvar" callback of the + wizard is safely ignored. # Casts $wiz onto $x. If $wiz isn't a signature, undef can't be returned. my $x; @@ -239,6 +292,15 @@ EXPORT "MGf_LOCAL" and "VMG_UVAR" are also only exported on request. They are all exported by the tags ':consts' and ':all'. +CAVEATS + If you store a magic object in the private data slot, the magic won't be + accessible by "getdata" since it's not copied by assignation. The only + way to address this would be to return a reference. + + If you define a wizard with a "free" callback and cast it on itself, + this destructor won't be called because the wizard will be destroyed + first. + DEPENDENCIES perl 5.7.3. @@ -252,15 +314,18 @@ 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. perltie and overload for other ways of enhancing objects. AUTHOR - Vincent Pit, "" + Vincent Pit, "", . - You can contact me by mail or on #perl @ FreeNode (Prof_Vince). + You can contact me by mail or on #perl @ FreeNode (vincent or + Prof_Vince). BUGS Please report any bugs or feature requests to "bug-variable-magic at @@ -274,6 +339,9 @@ SUPPORT perldoc Variable::Magic + Tests code coverage report is available at + . + COPYRIGHT & LICENSE Copyright 2007-2008 Vincent Pit, all rights reserved.