Long::Jump(3)

NAME
Long::Jump - Mechanism for returning to a specific point from a deeply nested stack.

DESCRIPTION
This module essentially provides a multi-level return. You can mark a spot with "setjump()" and then unwind the stack back to that point from any nested stack frame by name using "longjump()". You can also provide a list of return values.

This is not quite a match for C's long jump, but it is "close enough". It is safer than C's jump in that it only lets you escape frames by going up the stack, you cannot jump in other ways.

SYNOPSIS
    use Long::Jump qw/setjump longjump/;

    my $out = setjump foo => sub {
        bar();
        ...; # Will never get here
    };
    is($out, [qw/x y z/], "Got results of the long jump");

    $out = setjump foo => sub {
        print "Not calling longjump";
    };
    is($out, undef, "longjump was not called so we got an undef response");

    sub bar {
        baz();
        return 'bar'; # Will never get here
    }

    sub baz {
        bat();
        return 'baz'; # Will never get here
    }

    sub bat {
        my @out = qw/x y z/;
        longjump foo => @out;

        return 'bat'; # Will never get here
    }

EXPORTS

$out = setjump($NAME, sub { ... })
$out = setjump $NAME, sub { ... }
$out = setjump($NAME => sub { ... })
$out = setjump $NAME => sub { ... }
    Set a named point to which you will return when calling "longjump()". $out will be "undef" if "longjump()" was not called. $out will be an arrayref if "longjump()" was called. The $out arrayref will be empty, but present if "longjump()" is called without any return values.

    The return value will always be false if "longjump" was not called, and will always be true if it was called.

    You cannot nest multiple jump points with the same name, but you can nest multiple jump points if they have unqiue names. "longjump()" will always jump to the correct name.

longjump($NAME)
longjump $NAME
longjump($NAME, @RETURN_LIST)
longjump($NAME => @RETURN_LIST)
longjump $NAME => @RETURN_LIST
    Jump to the named point, optionally with values to return. This will throw exceptions if you use an invalid $NAME, which includes the case of calling it without a set jump point.

$bool = havejump($NAME)
$bool = havejump $NAME
    Check if a jump point with the given $NAME is currently set somewhere on the call stack. Returns a true value (1) if the named jump point is active and would be reachable via "longjump($NAME)", otherwise returns false (0).

    This is useful for code that wants to conditionally call "longjump()" only when an enclosing "setjump()" is actually present, avoiding the exception that would be thrown for an unknown name.

SOURCE
The source code repository for Long-Jump can be found at https://github.com/exodist/Long-Jump/.

MAINTAINERS

Chad Granum <exodist@cpan.org>

AUTHORS
Chad Granum <exodist@cpan.org>

COPYRIGHT
Copyright 2018 Chad Granum <exodist7@gmail.com>.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://dev.perl.org/licenses/