++ed by:
DOHERTY YUUKI
Author image Neil Bowers
and 1 contributors

NAME

UNIVERSAL::require - require() modules from a variable [deprecated]

SYNOPSIS

  # This only needs to be said once in your program.
  require UNIVERSAL::require;

  # Same as "require Some::Module"
  my $module = 'Some::Module';
  $module->require or die $@;

  # Same as "use Some::Module"
  BEGIN { $module->use or die $@ }

DESCRIPTION

Before using this module, you should look at the alternatives, some of which are listed in SEE ALSO below.

This module provides a safe mechanism for loading a module at runtime, when you have the name of the module in a variable.

If you've ever had to do this...

    eval "require $module";

to get around the bareword caveats on require(), this module is for you. It creates a universal require() class method that will work with every Perl module and its secure. So instead of doing some arcane eval() work, you can do this:

    $module->require;

It doesn't save you much typing, but it'll make a lot more sense to someone who's not a ninth level Perl acolyte.

Methods

require

  my $return_val = $module->require           or die $@;
  my $return_val = $module->require($version) or die $@;

This works exactly like Perl's require, except without the bareword restriction, and it doesn't die. Since require() is placed in the UNIVERSAL namespace, it will work on any module. You just have to use UNIVERSAL::require somewhere in your code.

Should the module require fail, or not be a high enough $version, it will simply return false and not die. The error will be in $@ as well as $UNIVERSAL::require::ERROR.

    $module->require or die $@;

use

    my $require_return = $module->use           or die $@;
    my $require_return = $module->use(@imports) or die $@;

Like UNIVERSAL::require, this allows you to use a $module without having to eval to work around the bareword requirement. It returns the same as require.

Should either the require or the import fail it will return false. The error will be in $@.

If possible, call this inside a BEGIN block to emulate a normal use as closely as possible.

    BEGIN { $module->use }

SECURITY NOTES

UNIVERSAL::require makes use of eval STRING. In previous versions of UNIVERSAL::require it was discovered that one could craft a class name which would result in code being executed. This hole has been closed. The only variables now exposed to eval STRING are the caller's package, filename and line which are not tainted.

UNIVERSAL::require is taint clean.

COPYRIGHT

Copyright 2001, 2005 by Michael G Schwern <schwern@pobox.com>.

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

See http://www.perl.com/perl/misc/Artistic.html

AUTHOR

Michael G Schwern <schwern@pobox.com>

Now maintained by Neil Bowers (NEILB).

SEE ALSO

Module::Load provides functions for loading code, and importing functions. It's actively maintained.

Module::Runtime provides a number of usesful functions for require'ing and use'ing modules, and associated operations.

Mojo::Loader is a class loader and plugin framework. Module::Loader is a stand-alone module that was inspired by Mojo::Loader.

There are many other modules that may be of interest on CPAN. An old review of some of them can be read at https://neilb.org/reviews/module-loading.html.

"require" in perlfunc.