NAME

Devel::Walk - Walk a complex object or reference.

SYNOPSIS

use Devel::Walk;

use Storable qw( freeze );

# We are looking for things that are unfreezable
sub unfreezable
{
    my( $location, $obj ) = @_;
    return unless ref $obj
    return if eval { local $SIG{__DIE__} = 'DEFAULT'; freeze $obj; 1; };
    warn "$location ($obj) is unfreezable";
    return 1;
}

walk( $suspect, \&unfreezable, '$obj' );

DESCRIPTION

Devel::Walk is used to recursely walk through a data structure, visiting each element in it one at a time. It keeps track of the location as a string that could, potentially, be used to delete or modify the structure.

walk

walk( $struct, $sub, '$basename' );

Recursely walks through $suspect, invoking $sub on each element of each structure. $basename is updated with each recursion to be. Only walks through ARRAY, HASH, SCALAR and REF references. Non-references and other references (CODE, GLOB, IO, etc) are passed over, though $sub is still invoked.

If $basename is empty, '$o' is used as a default.

For each element of the structure, $sub is invoked as follows:

$sub->( $location, $obj );

Where $obj is the current element of the structure being looked at and $location is a string that can be used to find the current value. Think of it as the address of the current object, but in perl format. You can use "eval" in perlfunc to find a value, provided $basename is available in the current context.

Example : "$o-{top}{second}[3]">

If $sub returns true, recursion will happen on that reference. If $sub returns false, recursion ends.

Devel::Walk will stop recursing when it detects circular references in your data structure. For example, in the following code, $foo will be seen first, so we don't walk through $foo-{foo}>.

my $foo = {biff=>1};
$foo->{foo} = $foo;
walk( $foo, sub { print "$_[0]\n"; 1 }, '$foo' );

Will only output:

$foo
$foo->{foo}
$foo->{biff}

SEE ALSO

Devel::Walk::Unstorable

AUTHOR

Philip Gwyn, <perl -at- pied.nu>

COPYRIGHT AND LICENSE

Copyright (C) 2025 by Philip Gwyn

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.26.3 or, at your option, any later version of Perl 5 you may have available.