Class: Delegator
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
|
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Inherits: | BasicObject |
Defined in: | lib/delegate.rb |
Overview
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
Notes
Be advised, RDoc will not detect delegated methods.
Class Method Summary
-
.new(obj) ⇒ Delegator
constructor
Pass in the obj to delegate method calls to.
Instance Method Summary
-
#!
Delegates ! to the _getobj_.
-
#!=(obj)
Returns true if two objects are not considered of equal value.
-
#==(obj)
Returns true if two objects are considered of equal value.
-
#__getobj__
This method must be overridden by subclasses and should return the object method calls are being delegated to.
-
#__setobj__(obj)
This method must be overridden by subclasses and change the object delegate to obj.
-
#freeze
Freeze both the object returned by _getobj_ and self.
-
#marshal_dump
Serialization support for the object returned by _getobj_.
-
#marshal_load(data)
Reinitializes delegation from a serialized object.
-
#method_missing(m, *args, &block)
Handles the magic of delegation through _getobj_.
-
#methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ methods.
-
#protected_methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ protected methods.
-
#public_methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ public methods.
-
#raise
Use __raise__ if your
Delegator
does not have a object to delegate the raise method call. -
#respond_to_missing?(m, include_private) ⇒ Boolean
Checks for a method provided by this the delegate object by forwarding the call through _getobj_.
-
#taint
Taint both the object returned by _getobj_ and self.
-
#trust
Trust both the object returned by _getobj_ and self.
-
#untaint
Untaint both the object returned by _getobj_ and self.
-
#untrust
Untrust both the object returned by _getobj_ and self.
Constructor Details
.new(obj) ⇒ Delegator
Pass in the obj to delegate method calls to. All methods supported by obj will be delegated to.
# File 'lib/delegate.rb', line 71
def initialize(obj) __setobj__(obj) end
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing(m, *args, &block)
Handles the magic of delegation through _getobj_.
# File 'lib/delegate.rb', line 78
def method_missing(m, *args, &block) r = true target = self.__getobj__ {r = false} if r && target.respond_to?(m) target.__send__(m, *args, &block) elsif ::Kernel.respond_to?(m, true) ::Kernel.instance_method(m).bind(self).(*args, &block) else super(m, *args, &block) end end
Instance Method Details
#!
Delegates ! to the _getobj_
# File 'lib/delegate.rb', line 151
def ! !__getobj__ end
#!=(obj)
Returns true if two objects are not considered of equal value.
# File 'lib/delegate.rb', line 143
def !=(obj) return false if obj.equal?(self) __getobj__ != obj end
#==(obj)
Returns true if two objects are considered of equal value.
# File 'lib/delegate.rb', line 135
def ==(obj) return true if obj.equal?(self) self.__getobj__ == obj end
#__getobj__
This method must be overridden by subclasses and should return the object method calls are being delegated to.
# File 'lib/delegate.rb', line 159
def __getobj__ __raise__ ::NotImplementedError, "need to define `__getobj__'" end
#__setobj__(obj)
This method must be overridden by subclasses and change the object delegate to obj.
# File 'lib/delegate.rb', line 167
def __setobj__(obj) __raise__ ::NotImplementedError, "need to define `__setobj__'" end
#freeze
Freeze both the object returned by _getobj_ and self.
# File 'lib/delegate.rb', line 230
rdoc_method :method: freeze
#marshal_dump
Serialization support for the object returned by _getobj_.
# File 'lib/delegate.rb', line 174
def marshal_dump ivars = instance_variables.reject {|var| /\A@delegate_/ =~ var} [ :__v2__, ivars, ivars.map{|var| instance_variable_get(var)}, __getobj__ ] end
#marshal_load(data)
Reinitializes delegation from a serialized object.
# File 'lib/delegate.rb', line 186
def marshal_load(data) version, vars, values, obj = data if version == :__v2__ vars.each_with_index{|var, i| instance_variable_set(var, values[i])} __setobj__(obj) else __setobj__(data) end end
#methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ methods.
# File 'lib/delegate.rb', line 110
def methods(all=true) __getobj__.methods(all) | super end
#protected_methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ protected methods.
# File 'lib/delegate.rb', line 126
def protected_methods(all=true) __getobj__.protected_methods(all) | super end
#public_methods(all = true)
Returns the methods available to this delegate object as the union of this object's and _getobj_ public methods.
# File 'lib/delegate.rb', line 118
def public_methods(all=true) __getobj__.public_methods(all) | super end
#raise
Use __raise__ if your Delegator
does not have a object to delegate the raise method call.
# File 'lib/delegate.rb', line 62
rdoc_method :method: raise
#respond_to_missing?(m, include_private) ⇒ Boolean
Checks for a method provided by this the delegate object by forwarding the call through _getobj_.
# File 'lib/delegate.rb', line 95
def respond_to_missing?(m, include_private) r = true target = self.__getobj__ {r = false} r &&= target.respond_to?(m, include_private) if r && include_private && !target.respond_to?(m, false) warn "#{caller(3)[0]}: delegator does not forward private method \##{m}" return false end r end
#taint
Taint both the object returned by _getobj_ and self.
# File 'lib/delegate.rb', line 215
rdoc_method :method: taint
#trust
Trust both the object returned by _getobj_ and self.
# File 'lib/delegate.rb', line 205
rdoc_method :method: trust
#untaint
Untaint both the object returned by _getobj_ and self.
# File 'lib/delegate.rb', line 220
rdoc_method :method: untaint
#untrust
Untrust both the object returned by _getobj_ and self.
# File 'lib/delegate.rb', line 210
rdoc_method :method: untrust