# CGI::Application::Standard::Config - - Define a standard configuration ... - perldoc - [phpMan]

    Last updated: Sat Feb 18 23:42:29 EST 2006

## NAME
    [CGI::Application::Standard::Config](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3AStandard%3A%3AConfig/markdown) -- Define a standard configuration API for [CGI::Application](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication/markdown)

## RATIONALE
    This module defines a minimum standard interface that configuration plugins for [CGI::Application](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication/markdown)
    should meet. Having such a standard allows other plugin authors to rely on basic configuration
    functionality without coding exceptions for several configuration modules, or giving up on such
    integration.

## SYNOPSIS
### For Average Users
    Simply load the config plugin before other modules that might use it:

      use [CGI::Application::Plugin::ConfigAuto](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3AConfigAuto/markdown);
      use [CGI::Application::Plugin::Session](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3ASession/markdown);

### For Configuration plugin authors
    Configuration plugin authors only need to follow the standards documented below.

### For other plugin authors who wish to rely on the standard
    Plugin authors who want to possibly use this standard can do so by simply using this module:

      package [CGI::Application::Plugin::Session](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3ASession/markdown);
      use [CGI::Application::Standard::Config](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3AStandard%3A%3AConfig/markdown);

    If a standards complaint config module hasn't already been loaded a stub for config() will be
    added which will safely return "undef".

   Example use by another plugin
    Here code first tries to get configuration details first from a config file, then from options
    passed to a plugin-specific config method, and finally applies defaults if no configuration
    options are found.

     my $session_options = $self->config('Session_options')
                                          || $self->session_config()
                                          || $self->session_defaults;

## Standard Interface Definition
    The following defines a minimum standard for configuration plugins to meet.

    Config plugins are free to provide to additional functionality.

    Configuration plugins are also encourage to explicitly document that they are using
    "[CGI::Application::Standard::Config](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3AStandard%3A%3AConfig/markdown)".

    If there are existing methods that follow the standard but have different names, you can use
    this example to always export your method:

      sub import {
        my $app = caller;
        no strict 'refs';
        my $full_name = $app . '::config';
        # Change cfg to your config()-compliant method name
        *$full_name = \&cfg;
        [CGI::Application::Plugin::YourNameHere](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3AYourNameHere/markdown)->export_to_level(1,@_);
      }

  $self->std_config
    This method should be exported by default to simply declare that you meet the standard report
    which version of the standard you meet. This simple implementation is recommended:

     sub std_config { return 1; }

  $self->config
    The intended use is to load to read-only configuration details once from a config file at start
    up time.

    This service is provided by plugins (list below). They must support at at least this syntax:

     my $value = $self->config('key');

    By default, config() simply returns undef, making it safe for other plugins to directly to check
    if "$self-"config('key')> returns the value it needs.

### config

    For applications that need little configuration, config() is not necessary-- using "PARAMS" in
    an instance script should suffice.

    Also, the param() is the appropriate method to use to set a configuration value at run time.

    Configuration plugins that provide at least this basic API include:

    [CGI::Application::Plugin::ConfigAuto](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication%3A%3APlugin%3A%3AConfigAuto/markdown).

   Standard config variables
    Users are encouraged to use these standard config variable names, to ease compatibility between
    plugins:

     ROOT_URI - A URI corresponding to the project root (<http://foo.com/proj> )
     ROOT_DIR - a file system path to the same location ( /home/joe/www/proj )

    All-caps are used to denote that config variables are essentially global constants.

    Why URI and not URL? The wikipedia explains:

      The contemporary point of view among the working group that oversees URIs is
      that the terms URL and URN are context-dependent aspects of URI and rarely
      need to be distinguished. Furthermore, the term URL is increasingly becoming
      obsolete, as it is rarely necessary to differentiate between URLs and URIs,
      in general.

## Standard Version
    This is 1.0 of the [CGI::Application](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication/markdown) config() standard.

## AUTHOR
    Written by Mark Stosberg <<mark@summersault.com>> with input from the [CGI::Application](https://www.chedong.com/phpMan.php/perldoc/CGI%3A%3AApplication/markdown) community.

COPYRIGHT and LICENSE
    Copyright (C) 2008, Mark Stosberg. All rights reserved.

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