Dancer::ModuleLoader - dynamic module loading helpers for Dancer core components
Taken directly from Dancer::Template::TemplateToolkit (which is core):
die "Template is needed by Dancer::Template::TemplateToolkit" unless Dancer::ModuleLoader->load('Template'); # we now have Template loaded
Sometimes in Dancer core we need to use modules, but we don't want to declare them all in advance in compile-time. These could be because the specific modules provide extra features which depend on code that isn't (and shouldn't) be in core, or perhaps because we only want these components loaded in lazy style, saving loading time a bit. For example, why load Template (which isn't required by Dancer) when you don't use Dancer::Template::TemplateToolkit?
To do such things takes a bit of code for localizing $@ and evaling. That code has been refactored into this module to help Dancer core developers.
$@
eval
Please only use this for Dancer core modules. If you're writing an external Dancer module (Dancer::Template::Tiny, Dancer::Session::Cookie, etc.), please simply "use ModuleYouNeed" in your code and don't use this module.
use ModuleYouNeed
Runs something like "use ModuleYouNeed" at runtime.
use Dancer::ModuleLoader; ... Dancer::ModuleLoader->load('Something') or die "Couldn't load Something\n"; # load version 5.0 or more Dancer::ModuleLoader->load('Something', '5.0') or die "Couldn't load Something\n"; # load version 5.0 or more my ($res, $error) = Dancer::ModuleLoader->load('Something', '5.0'); $res or die "Couldn't load Something : '$error'\n";
Takes in arguments the module name, and optionally the minimum version number required.
In scalar context, returns 1 if successful, 0 if not. In list context, returns 1 if successful, (0, "error message") if not.
(0, "error message")
If you need to give argumentto the loading module, please use the method load_with_params
load_with_params
Runs a "require ModuleYouNeed".
require ModuleYouNeed
use Dancer::ModuleLoader; ... Dancer::ModuleLoader->require('Something') or die "Couldn't require Something\n"; my ($res, $error) = Dancer::ModuleLoader->require('Something'); $res or die "Couldn't require Something : '$error'\n";
If you are unsure what you need (require or load), learn the differences between require and use.
require
load
use
Takes in arguments the module name.
Runs a "use ModuleYouNeed qw(param1 param2 ...)".
use ModuleYouNeed qw(param1 param2 ...)
use Dancer::ModuleLoader; ... Dancer::ModuleLoader->load_with_params('Something', qw(param1 param2) ) or die "Couldn't load Something with param1 and param2\n"; my ($res, $error) = Dancer::ModuleLoader->load_with_params('Something', @params); $res or die "Couldn't load Something with @params: '$error'\n";
Takes in arguments the module name, and optionally parameters to pass to the import internal method.
Runs a "use lib qw(path1 path2)" at run time instead of compile time.
use lib qw(path1 path2)
use Dancer::ModuleLoader; ... Dancer::ModuleLoader->use_lib('path1', @other_paths) or die "Couldn't perform use lib\n"; my ($res, $error) = Dancer::ModuleLoader->use_lib('path1', @other_paths); $res or die "Couldn't perform use lib : '$error'\n";
Takes in arguments a list of path to be prepended to @INC, in a similar way than use lib. However, this is performed at run time, so the list of paths can be generated and dynamic.
@INC
use lib
Given a setting in Dancer::Config, composes the class it should be.
This is the function that translates:
# in config.yaml template: "template_toolkit"
To the class:
Dancer::Template::TemplateToolkit
Example:
use Dancer::ModuleLoader; my $class = Dancer::ModuleLoader->class_from_setting( 'Dancer::Template' => 'template_toolkit', ); # $class == 'Dancer::Template::TemplateToolkit $class = Dancer::ModuleLoader->class_from_setting( 'Dancer::Template' => 'tiny', ); # class == 'Dancer::Template::Tiny
Module::Load, Module::New::Loader
Alexis Sukrieh
Copyright 2009-2010 Alexis Sukrieh.
This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
To install Dancer, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Dancer
CPAN shell
perl -MCPAN -e shell install Dancer
For more information on module installation, please visit the detailed CPAN module installation guide.