Module: Juicer::Chainable

Included in:
CssCacheBuster, ImageEmbed, Merger::Base, Minifyer::ClosureCompiler, Minifyer::YuiCompressor
Defined in:
lib/juicer/chainable.rb

Overview

Facilitates the chain of responsibility pattern. Wraps given methods and calls them in a chain.

To make an object chainable, simply include the module and call the class method chain_method for each method that should be chained.

Example is a simplified version of the Wikipedia one (http://en.wikipedia.org/wiki/Chain-of-responsibility_pattern)

class Logger include Juicer::Chainable

ERR = 3
NOTICE = 5
DEBUG = 7

def initialize(level)
 @level = level
end

def log(str, level)
 if level <= @level
   write str
 else
   abort_chain
 end
end

def write(str)
 puts str
end

chain_method :message

end

class EmailLogger < Logger def write(str) p "Logging by email" # ... end end

logger = Logger.new(Logger::NOTICE) logger.next_in_chain = EmailLogger.new(Logger::ERR)

logger.log("Some message", Logger::DEBUG) # Ignored logger.log("A warning", Logger::NOTICE) # Logged to console logger.log("An error", Logger::ERR) # Logged to console and email

Defined Under Namespace

Modules: ClassMethods

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object

Add the chain_method to classes that includes the module



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# File 'lib/juicer/chainable.rb', line 57

def self.included(base)
  base.extend(ClassMethods)
end

Instance Method Details

#next_in_chain ⇒ Object

Get next command in chain



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# File 'lib/juicer/chainable.rb', line 74

def next_in_chain
  @_next_in_chain ||= nil
  @_next_in_chain
end

#next_in_chain=(next_obj) ⇒ Object Also known as: set_next

Sets the next command in the chain



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# File 'lib/juicer/chainable.rb', line 64

def next_in_chain=(next_obj)
  @_next_in_chain = next_obj
  next_obj || self
end