NAME

Binding - eval with variable binding of caller stacks.

VERSION

This document describes Binding version 0.01

SYNOPSIS

use Binding;

sub inc_x {
    my $b = Binding->of_caller;
    $b->eval('$x + 1');
}

sub fortytwo {
    my $x = 41;
    inc_x;
}

sub two {
    my $x = 1;
    inc_x;
}

# You probably get the idea now...

DESCRIPTION

This module can help when you need to eval code with caller's variable binding. It's similar to Tcl's uplevel function. The name comes from the Binding class of Ruby language.

It's not doing much yet but let you grab caller variables.

INTERFACE

of_caller([ $level ])

One of the constructors. The $level parameter is optional and defaults to 1, which means one level up in the stack. The returned value is a object of Binding class, which can latter be invoked with eval method.

eval( $code_str )

An instance method that evals code in $code_str. Block form of eval is not accepted. Variables used in $code_str will be referenced to the one lives the given caller frame.

# calculate $x + 5
sub x_add_five {
    # notice the single quotes here.
    Binding->of_caller->eval('$x + 5');
}

{
    my $x = 3;
    my $y = add_five;
}

var( $name )

Return the value of the variable named $name in the specified scope.

DEPENDENCIES

PadWalker, Data::Dump, Devel::Caller

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to bug-binding@rt.cpan.org, or through the web interface at http://rt.cpan.org.

The returned object of Binding->of_caller need to be used immediately, or at least in the same frame of its construction, which means that this doesn't do what it means yet:

sub add {
    my $x = 5;
    my $b = Binding->of_caller;

    # Expect the binding '$x' is to the one in caller of add()
    add_x($b);
}

sub add_x {
    my $binding = shift;

    # But this $x is referring to the one in add()
    $binding->eval('$x + 1')
}

my $x = 3;
add; # returns 6 instead of 4;

SEE ALSO

The standard Binding class in Ruby core: http://www.ruby-doc.org/core/classes/Binding.html, and the extended Binding class http://extensions.rubyforge.org/rdoc/classes/Binding.html.

AUTHOR

Kang-min Liu <gugod@gugod.org>

LICENCE AND COPYRIGHT

Copyright (c) 2008, Kang-min Liu <gugod@gugod.org>.

This is free software, licensed under:

The MIT (X11) License

DISCLAIMER OF WARRANTY

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