Provided by: libpadwalker-perl_2.5-1build6_amd64 bug

NAME

       PadWalker - play with other peoples' lexical variables

SYNOPSIS

         use PadWalker qw(peek_my peek_our peek_sub closed_over);
         ...

DESCRIPTION

       PadWalker is a module which allows you to inspect (and even change!)  lexical variables in any subroutine
       which called you. It will only show those variables which are in scope at the point of the call.

       PadWalker is particularly useful for debugging. It's even used by Perl's built-in debugger. (It can also
       be used for evil, of course.)

       I wouldn't recommend using PadWalker directly in production code, but it's your call. Some of the modules
       that use PadWalker internally are certainly safe for and useful in production.

       peek_my LEVEL
       peek_our LEVEL
           The  LEVEL  argument  is  interpreted  just  like  the argument to "caller".  So peek_my(0) returns a
           reference to a hash of all the "my" variables that are  currently  in  scope;  peek_my(1)  returns  a
           reference  to  a  hash of all the "my" variables that are in scope at the point where the current sub
           was called, and so on.

           "peek_our" works in the same way, except that it lists the  "our"  variables  rather  than  the  "my"
           variables.

           The  hash associates each variable name with a reference to its value. The variable names include the
           sigil, so the variable $x is represented by the string '$x'.

           For example:

             my $x = 12;
             my $h = peek_my (0);
             ${$h->{'$x'}}++;

             print $x;  # prints 13

           Or a more complex example:

             sub increment_my_x {
               my $h = peek_my (1);
               ${$h->{'$x'}}++;
             }

             my $x=5;
             increment_my_x;
             print $x;  # prints 6

       peek_sub SUB
           The "peek_sub" routine takes a coderef as its argument, and returns a hash of the "my" variables used
           in that sub. The values will usually be undefined unless the sub is in use (i.e. in  the  call-chain)
           at the time. On the other hand:

             my $x = "Hello!";
             my $r = peek_sub(sub {$x})->{'$x'};
             print "$$r\n";        # prints 'Hello!'

           If  the  sub defines several "my" variables with the same name, you'll get the last one. I don't know
           of any use for "peek_sub" that isn't broken as a result of this, and it will probably  be  deprecated
           in a future version in favour of some alternative interface.

       closed_over SUB
           "closed_over"  is  similar to "peek_sub", except that it only lists the "my" variables which are used
           in the subroutine but defined outside: in other words, the variables which it closes over. This  does
           have  reasonable  uses:  see Data::Dump::Streamer, for example (a future version of which may in fact
           use "closed_over").

       set_closed_over SUB, HASH_REF
           "set_closed_over" reassigns the pad variables that are closed over by the subroutine.

           The second argument is a hash of references, much like the one returned from "closed_over".

       var_name LEVEL, VAR_REF
       var_name SUB,   VAR_REF
           "var_name(sub, var_ref)" returns the name of the variable referred to by "var_ref", provided it is  a
           "my"  variable  used  in  the sub. The "sub" parameter can be either a CODE reference or a number. If
           it's a number, it's treated the same way as the argument to "peek_my".

           For example,

             my $foo;
             print var_name(0, \$foo);    # prints '$foo'

             sub my_name {
               return var_name(1, shift);
             }
             print my_name(\$foo);        # ditto

AUTHOR

       Robin Houston <robin@cpan.org>

       With contributions from Richard Soberberg, Jesse Luehrs and Yuval Kogman, bug-spotting from Peter  Scott,
       Dave Mitchell and Goro Fuji, and suggestions from demerphq.

SEE ALSO

       Devel::LexAlias, Devel::Caller, Sub::Parameters

COPYRIGHT

       Copyright  (c)  2000-2009,  Robin  Houston. All Rights Reserved.  This module is free software. It may be
       used, redistributed and/or modified under the same terms as Perl itself.

perl v5.38.2                                       2024-03-31                                     PadWalker(3pm)