BasicObject
This library provides three different ways to delegate method calls to an object. The easiest to use is SimpleDelegator. Pass an object to the constructor and all methods supported by the object will be delegated. This object can be changed later.
Going a step further, the top level DelegateClass method allows you to easily setup delegation through class inheritance. This is considerably more flexible and thus probably the most common use for this library.
Finally, if you need full control over the delegation scheme, you can inherit from the abstract class Delegator and customize as needed. (If you find yourself needing this control, have a look at Forwardable which is also in the standard library. It may suit your needs better.)
SimpleDelegator’s implementation serves as a nice example of the use of Delegator:
class SimpleDelegator < Delegator def __getobj__ @delegate_sd_obj # return object we are delegating to, required end def __setobj__(obj) @delegate_sd_obj = obj # change delegation object, # a feature we're providing end end
Be advised, RDoc will not detect delegated methods.
# File delegate.rb, line 78 def method_missing(m, *args, &block) r = true target = self.__getobj__ {r = false} if r && target_respond_to?(target, m, false) target.__send__(m, *args, &block) elsif ::Kernel.method_defined?(m) || ::Kernel.private_method_defined?(m) ::Kernel.instance_method(m).bind_call(self, *args, &block) else super(m, *args, &block) end end
Use #__raise__ if your Delegator does not have a object to delegate the raise method call.
# File delegate.rb, line 67
Checks for a method provided by this the delegate object by forwarding the call through _getobj_.
# File delegate.rb, line 95 def respond_to_missing?(m, include_private) r = true target = self.__getobj__ {r = false} r &&= target_respond_to?(target, m, include_private) if r && include_private && !target_respond_to?(target, m, false) warn "delegator does not forward private method \##{m}", uplevel: 3 return false end r end