Class: Delegator
- 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:
require 'delegate'
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.
Direct Known Subclasses
Constant Summary collapse
- VERSION =
"0.2.0"
Class Method Summary collapse
-
.const_missing(n) ⇒ Object
:stopdoc:.
-
.delegating_block(mid) ⇒ Object
:nodoc:.
-
.public_api ⇒ Object
:nodoc:.
Instance Method Summary collapse
-
#! ⇒ Object
Delegates ! to the _getobj_.
-
#!=(obj) ⇒ Object
Returns true if two objects are not considered of equal value.
-
#==(obj) ⇒ Object
Returns true if two objects are considered of equal value.
-
#__getobj__ ⇒ Object
This method must be overridden by subclasses and should return the object method calls are being delegated to.
-
#__setobj__(obj) ⇒ Object
This method must be overridden by subclasses and change the object delegate to obj.
-
#eql?(obj) ⇒ Boolean
Returns true if two objects are considered of equal value.
-
#freeze ⇒ Object
:method: freeze Freeze both the object returned by _getobj_ and self.
-
#initialize(obj) ⇒ Delegator
constructor
Pass in the obj to delegate method calls to.
-
#marshal_dump ⇒ Object
Serialization support for the object returned by _getobj_.
-
#marshal_load(data) ⇒ Object
Reinitializes delegation from a serialized object.
-
#methods(all = true) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ methods.
-
#protected_methods(all = true) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ protected methods.
-
#public_methods(all = true) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ public methods.
-
#respond_to_missing?(m, include_private) ⇒ Boolean
Checks for a method provided by this the delegate object by forwarding the call through _getobj_.
Constructor Details
#initialize(obj) ⇒ Delegator
Pass in the obj to delegate method calls to. All methods supported by obj will be delegated to.
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# File 'lib/delegate.rb', line 75 def initialize(obj) __setobj__(obj) end |
Class Method Details
.const_missing(n) ⇒ Object
:stopdoc:
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# File 'lib/delegate.rb', line 60 def self.const_missing(n) ::Object.const_get(n) end |
.delegating_block(mid) ⇒ Object
:nodoc:
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# File 'lib/delegate.rb', line 346 def Delegator.delegating_block(mid) # :nodoc: lambda do |*args, &block| target = self.__getobj__ target.__send__(mid, *args, &block) end.ruby2_keywords end |
.public_api ⇒ Object
:nodoc:
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# File 'lib/delegate.rb', line 243 def self.public_api # :nodoc: @delegator_api end |
Instance Method Details
#! ⇒ Object
Delegates ! to the _getobj_
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# File 'lib/delegate.rb', line 180 def ! !__getobj__ end |
#!=(obj) ⇒ Object
Returns true if two objects are not considered of equal value.
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# File 'lib/delegate.rb', line 164 def !=(obj) return false if obj.equal?(self) __getobj__ != obj end |
#==(obj) ⇒ Object
Returns true if two objects are considered of equal value.
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# File 'lib/delegate.rb', line 156 def ==(obj) return true if obj.equal?(self) self.__getobj__ == obj end |
#__getobj__ ⇒ Object
This method must be overridden by subclasses and should return the object method calls are being delegated to.
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# File 'lib/delegate.rb', line 188 def __getobj__ __raise__ ::NotImplementedError, "need to define `__getobj__'" end |
#__setobj__(obj) ⇒ Object
This method must be overridden by subclasses and change the object delegate to obj.
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# File 'lib/delegate.rb', line 196 def __setobj__(obj) __raise__ ::NotImplementedError, "need to define `__setobj__'" end |
#eql?(obj) ⇒ Boolean
Returns true if two objects are considered of equal value.
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# File 'lib/delegate.rb', line 172 def eql?(obj) return true if obj.equal?(self) obj.eql?(__getobj__) end |
#freeze ⇒ Object
:method: freeze Freeze both the object returned by _getobj_ and self.
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# File 'lib/delegate.rb', line 237 def freeze __getobj__.freeze super() end |
#marshal_dump ⇒ Object
Serialization support for the object returned by _getobj_.
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# File 'lib/delegate.rb', line 203 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) ⇒ Object
Reinitializes delegation from a serialized object.
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# File 'lib/delegate.rb', line 215 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) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ methods.
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# File 'lib/delegate.rb', line 131 def methods(all=true) __getobj__.methods(all) | super end |
#protected_methods(all = true) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ protected methods.
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# File 'lib/delegate.rb', line 147 def protected_methods(all=true) __getobj__.protected_methods(all) | super end |
#public_methods(all = true) ⇒ Object
Returns the methods available to this delegate object as the union of this object’s and _getobj_ public methods.
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# File 'lib/delegate.rb', line 139 def public_methods(all=true) __getobj__.public_methods(all) | super end |
#respond_to_missing?(m, include_private) ⇒ Boolean
Checks for a method provided by this the delegate object by forwarding the call through _getobj_.
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# File 'lib/delegate.rb', line 99 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 |