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okay.

The first parameter is the block of code to run. This is protoyped as C< & > so
you can replace the usual 'sub { ... }' with 'callback { ... }'. If you already
have a coderef, you can pass that using C< &callback($code, ...) >, but please
don't.

Remaining parameters are optional - you can either pass a single array, containing
a list of the B<names> of the variables that are safe to capture:

 callback { print "$x\n" } [qw($x)];

or a list of named parameters:

=over 4

=item * weaken => [...] - list of B<variable names> which will be copied, weakened
via L<Scalar::Util/weaken>, then prepended to the parameter list available in @_
in your code block

=item * allowed => [...] - list of B<variable names> to ignore if used in the code,
same behaviour as passing a single arrayref

=back

For example, a method call might look like this:

 my $code = callback {
   my $self = shift;
   $self->method(@_);
 } weaken => [qw($self)];

although L<curry::weak> would be a much cleaner alternative there:

 my $code = $self->curry::weak::method;

You can mix C<weaken> and C<allowed>:

 my $x = 1;
 my $code = callback {
   shift->method(++$x);
 } weaken => [qw($self)], allowed => [qw($x)];

=head2 lint

Runs checks on the given coderef. This is used internally and not exported,
but if you just want to get a list of potential problems for a coderef,
call this:

 my @errors = lint($code, allowed => [qw($x)]);

It's unlikely that the C<weaken> parameter will work when calling this
function directly - this may be fixed in a future version.

=head1 SEE ALSO

=over 4

=item * L<curry> - provides a convenient interface for creating callbacks

=item * L<PadWalker> - does most of the real work behind this module

=item * L<Test::RefCount> - convenient testing for reference counts, makes
cycles easier to detect in test code

=item * L<Devel::Cycle> - reports whether cycles exist and provides useful
diagnostics when any are found

=back

=head1 INHERITED METHODS

=over 4

=item L<Exporter>

L<as_heavy|Exporter/as_heavy>, L<export|Exporter/export>, L<export_fail|Exporter/export_fail>, L<export_ok_tags|Exporter/export_ok_tags>, L<export_tags|Exporter/export_tags>, L<export_to_level|Exporter/export_to_level>, L<import|Exporter/import>, L<r...

=back

=head1 AUTHOR

Tom Molesworth <cpan@entitymodel.com>

=head1 LICENSE

Copyright Tom Molesworth 2012-2013. Licensed under the same terms as Perl itself.