---
title: Extending webgen
inMenu: true
---
h2. Extending webgen

h3. General

p={font-size: 150%; color: red}. *This part of the homepage is out of date and will be updated soon!*


There is a logging mechanism available for informational and debugging purposes. Four different log
levels are available:

* debug
* info
* warn
* error

The methods are named after the log levels and can be invoked by using
@logger.{debug|info|warn|error}@. You need to provide a string as argument or a block which returns
a string.

h3. Normal plugins (new tags, file handlers, etc)

As webgen is plugin-based, it can be extended very easily. A simple example is shown in the
<a href="{relocatable: tutorial.page#website-plugin}">tutorial</a>.

If you want more sophisticated examples of plugins, have a look at webgen itself and the plugins
that get shipped with it. They can be found in the directory @lib/webgen/plugins/@!

h3. CLI Command Plugins

For this you need to write a new command class and put its file into the @plugin@ folder of the
website. Have a look at the "cmdparse API reference":http://cmdparse.rubyforge.org/rdoc/index.html
for information about how to write a command class.

There are basically two ways for a command plugin:

* Easiest one

  You just declare a new class derived from @CmdParse::Command@ and include the
  @Webgen::CommandPlugin@ module. After you have included this module, you can use all standard
  plugin directives, like @summary@ or @add_param@. Also, this command gets automatically added to
  the main @CommandParser@ class. Thus, the @initialize@ method must not take any arguments!

  <pre>
  class SimpleCommand < CmdParse::Command

  include Webgen::CommandPlugin

  summary "Describe simple command"
  add_param 'firstParam', 45, 'Description of firstParam'

  def initialize
    super( 'simple', false )
    self.short_desc = "This is a sample for a simple command."
  end

  def usage; "Usage: #{@options.program_name} [global options] simple"; end

  def execute( args )
    # do something useful
  end

  end
  </pre>

* Easy one

  You only need to go this way when the @initialize@ method of your command class needs to
  arguments!!

  Like before, you declare your new command class. This time however, you need include the
  @Webgen::PluginDefs@ module and set the constant @VIRTUAL@ to true. This prevents the plugin
  system from automatically instantiating an object. You then need to instantiate an object and add
  it to the main @CommandParser@ class. This can be done by calling the @add_cmdparser_command@ of
  the configuration plugin.

  <pre>
  class OtherCommand < CmdParse::Command

  include Webgen::PluginDefs

  VIRTUAL = true

  summary "Describe other simple command"

  def initialize( arg )
    super( 'otherSimple', false )
    @arg = arg
    self.short_desc = "This is a second sample for a simple command."
  end

  def usage; "Usage: #{@options.program_name} [global options] otherSimple"; end

  def execute( args )
    # do something useful
  end

  end

  Webgen::Plugin['Configuration'].add_cmdparser_command( OtherCommand.new( 5 ) )
  </pre>