Module: Properties

Defined in:
lib/sugar-high/properties.rb

Overview

From: www.infoq.com/articles/properties-metaprogramming

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.extended(base) ⇒ Object 



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# File 'lib/sugar-high/properties.rb', line 4

def self.extended(base)
  base.class_eval %{
    def fire_event_for(sym, arg)
      return if !@listener[sym]
      @listener[sym].each {|l| l.call(arg) }
    end
  }
end

Instance Method Details

#is(test) ⇒ Object 



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# File 'lib/sugar-high/properties.rb', line 37

def is(test)
  lambda {|val| test === val }
end

#property(sym, predicate = nil) ⇒ Object

def property(sym, &predicate)



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# File 'lib/sugar-high/properties.rb', line 14

def property(sym, predicate=nil)
  define_method(sym) do
    instance_variable_get("@#{sym}")
  end

  define_method("#{sym}=") do |arg|
    return if !predicate.call(arg) if predicate
    instance_variable_set("@#{sym}", arg)
    fire_event_for(sym, arg)
  end

  define_method("add_#{sym}_listener") do |x|
    @listener ||= {}
    @listener[sym] ||= []
    @listener[sym] << x
  end

  define_method("remove_#{sym}_listener") do |x|
    return if !@listener[sym]
    @listener[sym].delete_at(x)
  end
end