Variable::Magic - Associate user-defined magic to variables from Perl.
VERSION
- Version 0.29
+ Version 0.30
SYNOPSIS
use Variable::Magic qw/wizard cast dispell/;
True iff this module could have been built with thread-safety features
enabled.
+ "VMG_OP_INFO_NAME"
+ Value to pass with "op_info" to get the current op name in the magic
+ callbacks.
+
+ "VMG_OP_INFO_OBJECT"
+ Value to pass with "op_info" to get a "B::OP" object representing the
+ current op in the magic callbacks.
+
FUNCTIONS
"wizard"
wizard sig => ...,
data => sub { ... },
- get => sub { my ($ref, $data) = @_; ... },
- set => sub { my ($ref, $data) = @_; ... },
- len => sub { my ($ref, $data, $len) = @_; ... ; return $newlen; },
- clear => sub { my ($ref, $data) = @_; ... },
- free => sub { my ($ref, $data) = @_, ... },
- copy => sub { my ($ref, $data, $key, $elt) = @_; ... },
- local => sub { my ($ref, $data) = @_; ... },
- fetch => sub { my ($ref, $data, $key) = @_; ... },
- store => sub { my ($ref, $data, $key) = @_; ... },
- exists => sub { my ($ref, $data, $key) = @_; ... },
- delete => sub { my ($ref, $data, $key) = @_; ... },
- copy_key => $bool
+ get => sub { my ($ref, $data [, $op]) = @_; ... },
+ set => sub { my ($ref, $data [, $op]) = @_; ... },
+ len => sub { my ($ref, $data, $len [, $op]) = @_; ... ; return $newlen; },
+ clear => sub { my ($ref, $data [, $op]) = @_; ... },
+ free => sub { my ($ref, $data [, $op]) = @_, ... },
+ copy => sub { my ($ref, $data, $key, $elt [, $op]) = @_; ... },
+ local => sub { my ($ref, $data [, $op]) = @_; ... },
+ fetch => sub { my ($ref, $data, $key [, $op]) = @_; ... },
+ store => sub { my ($ref, $data, $key [, $op]) = @_; ... },
+ exists => sub { my ($ref, $data, $key [, $op]) = @_; ... },
+ delete => sub { my ($ref, $data, $key [, $op]) = @_; ... },
+ copy_key => $bool,
+ op_info => [ 0 | VMG_OP_INFO_NAME | VMG_OP_INFO_OBJECT ]
This function creates a 'wizard', an opaque type that holds the magic
information. It takes a list of keys / values as argument, whose keys
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). Other
- arguments are specific to the magic hooked :
+ (or "undef" when no private data constructor was supplied).
+
+ Moreover, when you pass "op_info => $num" to "wizard", the last
+ element of @_ will be the current op name if "$num ==
+ VMG_OP_INFO_NAME" and a "B::OP" object representing the current op
+ if "$num == VMG_OP_INFO_OBJECT". Both have a performance hit, but
+ just getting the name is lighter than getting the op object.
+
+ Other arguments are specific to the magic hooked :
* "len"
my $x;
die 'error' unless cast $x, $wiz;
+ The "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
+ "POSIX::tzset" each time the 'TZ' environment variable is changed in
+ %ENV, you can use :
+
+ use POSIX;
+ cast $ENV{TZ}, wizard set => sub { POSIX::tzset(); () };
+
+ If you want to overcome the possible deletion of the 'TZ' entry, you
+ have no choice but to rely on "store" uvar magic.
+
"getdata"
getdata [$@%&*]var, [$wiz|$sig]