acme::damn(3pm) [debian man page]
Damn(3pm) User Contributed Perl Documentation Damn(3pm) NAME
Acme::Damn - 'Unbless' Perl objects. SYNOPSIS
use Acme::Damn; my $ref = ... some reference ... my $obj = bless $ref , 'Some::Class'; ... do something with your object ... $ref = damn $obj; # recover the original reference (unblessed) ... neither $ref nor $obj are Some::Class objects ... DESCRIPTION
Acme::Damn provides a single routine, damn(), which takes a blessed reference (a Perl object), and unblesses it, to return the original reference. EXPORT By default, Acme::Damn exports the method damn() into the current namespace. Aliases for damn() (see below) may be imported upon request. Methods damn object damn() accepts a single blessed reference as its argument, and returns that reference unblessed. If object is not a blessed reference, then damn() will "die" with an error. bless reference bless reference [ , package ] bless reference [ , undef ] Optionally, Acme::Damn will modify the behaviour of "bless" to allow the passing of an explicit "undef" as the target package to invoke damn(): use Acme::Damn qw( bless ); my $obj = ... some blessed reference ...; # the following statements are equivalent my $ref = bless $obj , undef; my $ref = damn $obj; NOTE: The modification of "bless" is lexically scoped to the current package, and is not global. Method Aliases Not everyone likes to damn the same way or in the same language, so Acme::Damn offers the ability to specify any alias on import, provided that alias is a valid Perl subroutine name (i.e. all characters match "w"). use Acme::Damn qw( unbless ); use Acme::Damn qw( foo ); use Acme::Damn qw( unblessthyself ); use Acme::Damn qw( recant ); Version 0.02 supported a defined list of aliases, and this has been replaced in v0.03 by the ability to import any alias for "damn()". WARNING
Just as "bless" doesn't call an object's initialisation code, "damn" doesn't invoke an object's "DESTROY" method. For objects that need to be "DESTROY"ed, either don't "damn" them, or call "DESTROY" before judgement is passed. ACKNOWLEDGEMENTS
Thanks to Claes Jacobsson <claes@surfar.nu> for suggesting the use of aliases, and Bo Lindbergh <blgl@cpan.org> for the suggested modification of "bless". SEE ALSO
bless, perlboot, perltoot, perltooc, perlbot, perlobj. AUTHOR
Ian Brayshaw, <ian@onemore.org> COPYRIGHT AND LICENSE
Copyright 2003-2012 Ian Brayshaw This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2012-02-14 Damn(3pm)
Check Out this Related Man Page
Scalar::Util(3pm) Perl Programmers Reference Guide Scalar::Util(3pm) NAME
Scalar::Util - A selection of general-utility scalar subroutines SYNOPSIS
use Scalar::Util qw(blessed dualvar isweak readonly refaddr reftype tainted weaken isvstring looks_like_number set_prototype); # and other useful utils appearing below DESCRIPTION
"Scalar::Util" contains a selection of subroutines that people have expressed would be nice to have in the perl core, but the usage would not really be high enough to warrant the use of a keyword, and the size so small such that being individual extensions would be wasteful. By default "Scalar::Util" does not export any subroutines. The subroutines defined are blessed EXPR If EXPR evaluates to a blessed reference the name of the package that it is blessed into is returned. Otherwise "undef" is returned. $scalar = "foo"; $class = blessed $scalar; # undef $ref = []; $class = blessed $ref; # undef $obj = bless [], "Foo"; $class = blessed $obj; # "Foo" dualvar NUM, STRING Returns a scalar that has the value NUM in a numeric context and the value STRING in a string context. $foo = dualvar 10, "Hello"; $num = $foo + 2; # 12 $str = $foo . " world"; # Hello world isvstring EXPR If EXPR is a scalar which was coded as a vstring the result is true. $vs = v49.46.48; $fmt = isvstring($vs) ? "%vd" : "%s"; #true printf($fmt,$vs); isweak EXPR If EXPR is a scalar which is a weak reference the result is true. $ref = $foo; $weak = isweak($ref); # false weaken($ref); $weak = isweak($ref); # true NOTE: Copying a weak reference creates a normal, strong, reference. $copy = $ref; $weak = isweak($copy); # false looks_like_number EXPR Returns true if perl thinks EXPR is a number. See "looks_like_number" in perlapi. openhandle FH Returns FH if FH may be used as a filehandle and is open, or FH is a tied handle. Otherwise "undef" is returned. $fh = openhandle(*STDIN); # *STDIN $fh = openhandle(*STDIN); # *STDIN $fh = openhandle(*NOTOPEN); # undef $fh = openhandle("scalar"); # undef readonly SCALAR Returns true if SCALAR is readonly. sub foo { readonly($_[0]) } $readonly = foo($bar); # false $readonly = foo(0); # true refaddr EXPR If EXPR evaluates to a reference the internal memory address of the referenced value is returned. Otherwise "undef" is returned. $addr = refaddr "string"; # undef $addr = refaddr $var; # eg 12345678 $addr = refaddr []; # eg 23456784 $obj = bless {}, "Foo"; $addr = refaddr $obj; # eg 88123488 reftype EXPR If EXPR evaluates to a reference the type of the variable referenced is returned. Otherwise "undef" is returned. $type = reftype "string"; # undef $type = reftype $var; # SCALAR $type = reftype []; # ARRAY $obj = bless {}, "Foo"; $type = reftype $obj; # HASH set_prototype CODEREF, PROTOTYPE Sets the prototype of the given function, or deletes it if PROTOTYPE is undef. Returns the CODEREF. set_prototype &foo, '$$'; tainted EXPR Return true if the result of EXPR is tainted $taint = tainted("constant"); # false $taint = tainted($ENV{PWD}); # true if running under -T weaken REF REF will be turned into a weak reference. This means that it will not hold a reference count on the object it references. Also when the reference count on that object reaches zero, REF will be set to undef. This is useful for keeping copies of references , but you don't want to prevent the object being DESTROY-ed at its usual time. { my $var; $ref = $var; weaken($ref); # Make $ref a weak reference } # $ref is now undef Note that if you take a copy of a scalar with a weakened reference, the copy will be a strong reference. my $var; my $foo = $var; weaken($foo); # Make $foo a weak reference my $bar = $foo; # $bar is now a strong reference This may be less obvious in other situations, such as "grep()", for instance when grepping through a list of weakened references to objects that may have been destroyed already: @object = grep { defined } @object; This will indeed remove all references to destroyed objects, but the remaining references to objects will be strong, causing the remaining objects to never be destroyed because there is now always a strong reference to them in the @object array. DIAGNOSTICS
Module use may give one of the following errors during import. Weak references are not implemented in the version of perl The version of perl that you are using does not implement weak references, to use "isweak" or "weaken" you will need to use a newer release of perl. Vstrings are not implemented in the version of perl The version of perl that you are using does not implement Vstrings, to use "isvstring" you will need to use a newer release of perl. "NAME" is only available with the XS version of Scalar::Util "Scalar::Util" contains both perl and C implementations of many of its functions so that those without access to a C compiler may still use it. However some of the functions are only available when a C compiler was available to compile the XS version of the extension. At present that list is: weaken, isweak, dualvar, isvstring, set_prototype KNOWN BUGS
There is a bug in perl5.6.0 with UV's that are >= 1<<31. This will show up as tests 8 and 9 of dualvar.t failing SEE ALSO
List::Util COPYRIGHT
Copyright (c) 1997-2007 Graham Barr <gbarr@pobox.com>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. Except weaken and isweak which are Copyright (c) 1999 Tuomas J. Lukka <lukka@iki.fi>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as perl itself. perl v5.16.2 2012-10-11 Scalar::Util(3pm)