Acme-Lexical-Thief
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DESCRIPTION
This package allows you access to your caller's lexical variables, without
them knowing! Full read/write access. This is generally a pretty bad idea,
hence the Acme namespace.
You can steal scalars, arrays and hashes:
steal $car, @treasures, %stash;
Parentheses can surround the list of variables to steal:
steal ($car, @treasures, %stash);
Generally everything should "just work" as you expect it to. Except when
it does not.
Technically speaking, your stolen $car is a package-scoped (`our`)
variable which is lexically aliased (`local *car`) to the caller's
variable of the same name. Because `steal` is parsed at compile-time, you
don't need to (and indeed should not!) pre-declare your stolen variables.
sub greet_verbally {
my $name; # don't do this!
steal $name;
say "Hello $name";
}
By default, this module steals from your *immediate* caller. You can
thieve higher up the call stack using:
steal 0 ($car); # caller's $car
steal 1 @boats; # caller's caller's @boats
steal 2 %stash; # caller's caller's caller's @stash
You cannot indicate the level you wish to steal from using a variable; it
must be a literal integer in your source code. (It can be in decimal,
octal, hexadecimal or binary notation.) The integer must immediately
follow the `steal` keyword, and not be followed by a comma.
The `steal` keyword cannot be used in an expression; it must be a
standalone statement.
steal $foo;
if (defined $foo) { ... } # ok
if (steal $foo) { ... } # not this!
# this works...
if (do { steal $foo; defined $foo })
{
# ... but $foo won't exist in this block!
...
}
If you attempt to steal a variable which does not exist, then a run-time
exception will be thrown.
WHY YOU SHOULD NOT USE THIS MODULE
When people declare lexical (`my`) variables within a sub, they (quite
reasonably) expect these to stay local to the sub. If they rename those
variables, change them (say replacing a hashref with a hash), drop them or
whatever, then they don't expect code outside the sub to pay much
attention.
Peeking at your caller's lexicals breaks those expectations.
Peeking at your caller's lexicals leaks an abstraction.
Peeking at your caller's lexicals can cause spooky action at a distance.
Every time you peek at your caller's lexicals, a fairy dies.
Just think about that for a minute, won't you?
BUGS
Please report any bugs to
<http://rt.cpan.org/Dist/Display.html?Queue=Acme-Lexical-Thief>.
SEE ALSO
PadWalker - a slightly more sane alternative to peeking at your caller's
lexicals.
Data::Alias - a slightly more sane way of creating lexical aliases.
This package was initially published on PerlMonks as `Acme::Asplode`
<http://www.perlmonks.org/?node_id=1008814>, but I prefer the current
name.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2012 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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