mirror of
https://github.com/ruby/ruby.git
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6061003100
This commit prevents "method redefined" warnings when overriding methods
within a `DelegateClass` block, such as in the following example:
```ruby
Base = Class.new do
def foo
"foo"
end
end
Overridden = DelegateClass(Base) do
def foo
super + "!"
end
end
```
Fixes https://bugs.ruby-lang.org/issues/19047.
https://github.com/ruby/delegate/commit/214fae86de
446 lines
12 KiB
Ruby
446 lines
12 KiB
Ruby
# frozen_string_literal: true
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# = delegate -- Support for the Delegation Pattern
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#
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# Documentation by James Edward Gray II and Gavin Sinclair
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##
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# This library provides three different ways to delegate method calls to an
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# object. The easiest to use is SimpleDelegator. Pass an object to the
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# constructor and all methods supported by the object will be delegated. This
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# object can be changed later.
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#
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# Going a step further, the top level DelegateClass method allows you to easily
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# setup delegation through class inheritance. This is considerably more
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# flexible and thus probably the most common use for this library.
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#
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# Finally, if you need full control over the delegation scheme, you can inherit
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# from the abstract class Delegator and customize as needed. (If you find
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# yourself needing this control, have a look at Forwardable which is also in
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# the standard library. It may suit your needs better.)
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#
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# SimpleDelegator's implementation serves as a nice example of the use of
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# Delegator:
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#
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# require 'delegate'
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#
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# class SimpleDelegator < Delegator
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# def __getobj__
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# @delegate_sd_obj # return object we are delegating to, required
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# end
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#
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# def __setobj__(obj)
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# @delegate_sd_obj = obj # change delegation object,
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# # a feature we're providing
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# end
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# end
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#
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# == Notes
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#
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# Be advised, RDoc will not detect delegated methods.
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#
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class Delegator < BasicObject
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VERSION = "0.2.0"
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kernel = ::Kernel.dup
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kernel.class_eval do
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alias __raise__ raise
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[:to_s, :inspect, :!~, :===, :<=>, :hash].each do |m|
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undef_method m
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end
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private_instance_methods.each do |m|
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if /\Ablock_given\?\z|\Aiterator\?\z|\A__.*__\z/ =~ m
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next
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end
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undef_method m
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end
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end
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include kernel
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# :stopdoc:
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def self.const_missing(n)
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::Object.const_get(n)
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end
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# :startdoc:
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##
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# :method: raise
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# Use #__raise__ if your Delegator does not have a object to delegate the
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# #raise method call.
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#
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#
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# Pass in the _obj_ to delegate method calls to. All methods supported by
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# _obj_ will be delegated to.
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#
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def initialize(obj)
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__setobj__(obj)
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end
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#
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# Handles the magic of delegation through \_\_getobj\_\_.
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#
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ruby2_keywords def method_missing(m, *args, &block)
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r = true
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target = self.__getobj__ {r = false}
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if r && target_respond_to?(target, m, false)
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target.__send__(m, *args, &block)
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elsif ::Kernel.method_defined?(m) || ::Kernel.private_method_defined?(m)
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::Kernel.instance_method(m).bind_call(self, *args, &block)
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else
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super(m, *args, &block)
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end
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end
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#
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# Checks for a method provided by this the delegate object by forwarding the
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# call through \_\_getobj\_\_.
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#
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def respond_to_missing?(m, include_private)
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r = true
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target = self.__getobj__ {r = false}
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r &&= target_respond_to?(target, m, include_private)
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if r && include_private && !target_respond_to?(target, m, false)
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warn "delegator does not forward private method \##{m}", uplevel: 3
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return false
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end
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r
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end
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KERNEL_RESPOND_TO = ::Kernel.instance_method(:respond_to?)
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private_constant :KERNEL_RESPOND_TO
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# Handle BasicObject instances
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private def target_respond_to?(target, m, include_private)
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case target
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when Object
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target.respond_to?(m, include_private)
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else
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if KERNEL_RESPOND_TO.bind_call(target, :respond_to?)
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target.respond_to?(m, include_private)
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else
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KERNEL_RESPOND_TO.bind_call(target, m, include_private)
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end
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end
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end
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#
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# Returns the methods available to this delegate object as the union
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# of this object's and \_\_getobj\_\_ methods.
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#
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def methods(all=true)
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__getobj__.methods(all) | super
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end
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#
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# Returns the methods available to this delegate object as the union
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# of this object's and \_\_getobj\_\_ public methods.
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#
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def public_methods(all=true)
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__getobj__.public_methods(all) | super
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end
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#
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# Returns the methods available to this delegate object as the union
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# of this object's and \_\_getobj\_\_ protected methods.
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#
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def protected_methods(all=true)
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__getobj__.protected_methods(all) | super
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end
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# Note: no need to specialize private_methods, since they are not forwarded
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#
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# Returns true if two objects are considered of equal value.
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#
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def ==(obj)
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return true if obj.equal?(self)
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self.__getobj__ == obj
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end
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#
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# Returns true if two objects are not considered of equal value.
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#
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def !=(obj)
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return false if obj.equal?(self)
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__getobj__ != obj
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end
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#
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# Returns true if two objects are considered of equal value.
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#
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def eql?(obj)
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return true if obj.equal?(self)
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obj.eql?(__getobj__)
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end
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#
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# Delegates ! to the \_\_getobj\_\_
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#
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def !
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!__getobj__
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end
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#
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# This method must be overridden by subclasses and should return the object
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# method calls are being delegated to.
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#
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def __getobj__
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__raise__ ::NotImplementedError, "need to define `__getobj__'"
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end
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#
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# This method must be overridden by subclasses and change the object delegate
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# to _obj_.
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#
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def __setobj__(obj)
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__raise__ ::NotImplementedError, "need to define `__setobj__'"
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end
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#
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# Serialization support for the object returned by \_\_getobj\_\_.
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#
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def marshal_dump
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ivars = instance_variables.reject {|var| /\A@delegate_/ =~ var}
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[
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:__v2__,
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ivars, ivars.map {|var| instance_variable_get(var)},
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__getobj__
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]
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end
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#
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# Reinitializes delegation from a serialized object.
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#
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def marshal_load(data)
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version, vars, values, obj = data
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if version == :__v2__
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vars.each_with_index {|var, i| instance_variable_set(var, values[i])}
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__setobj__(obj)
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else
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__setobj__(data)
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end
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end
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def initialize_clone(obj, freeze: nil) # :nodoc:
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self.__setobj__(obj.__getobj__.clone(freeze: freeze))
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end
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def initialize_dup(obj) # :nodoc:
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self.__setobj__(obj.__getobj__.dup)
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end
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private :initialize_clone, :initialize_dup
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##
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# :method: freeze
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# Freeze both the object returned by \_\_getobj\_\_ and self.
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#
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def freeze
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__getobj__.freeze
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super()
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end
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@delegator_api = self.public_instance_methods
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def self.public_api # :nodoc:
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@delegator_api
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end
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end
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##
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# A concrete implementation of Delegator, this class provides the means to
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# delegate all supported method calls to the object passed into the constructor
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# and even to change the object being delegated to at a later time with
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# #__setobj__.
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#
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# class User
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# def born_on
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# Date.new(1989, 9, 10)
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# end
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# end
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#
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# require 'delegate'
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#
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# class UserDecorator < SimpleDelegator
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# def birth_year
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# born_on.year
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# end
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# end
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#
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# decorated_user = UserDecorator.new(User.new)
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# decorated_user.birth_year #=> 1989
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# decorated_user.__getobj__ #=> #<User: ...>
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#
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# A SimpleDelegator instance can take advantage of the fact that SimpleDelegator
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# is a subclass of +Delegator+ to call <tt>super</tt> to have methods called on
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# the object being delegated to.
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#
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# class SuperArray < SimpleDelegator
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# def [](*args)
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# super + 1
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# end
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# end
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#
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# SuperArray.new([1])[0] #=> 2
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#
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# Here's a simple example that takes advantage of the fact that
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# SimpleDelegator's delegation object can be changed at any time.
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#
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# class Stats
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# def initialize
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# @source = SimpleDelegator.new([])
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# end
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#
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# def stats(records)
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# @source.__setobj__(records)
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#
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# "Elements: #{@source.size}\n" +
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# " Non-Nil: #{@source.compact.size}\n" +
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# " Unique: #{@source.uniq.size}\n"
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# end
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# end
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#
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# s = Stats.new
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# puts s.stats(%w{James Edward Gray II})
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# puts
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# puts s.stats([1, 2, 3, nil, 4, 5, 1, 2])
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#
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# Prints:
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#
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# Elements: 4
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# Non-Nil: 4
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# Unique: 4
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#
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# Elements: 8
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# Non-Nil: 7
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# Unique: 6
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#
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class SimpleDelegator < Delegator
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# Returns the current object method calls are being delegated to.
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def __getobj__
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unless defined?(@delegate_sd_obj)
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return yield if block_given?
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__raise__ ::ArgumentError, "not delegated"
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end
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@delegate_sd_obj
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end
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#
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# Changes the delegate object to _obj_.
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#
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# It's important to note that this does *not* cause SimpleDelegator's methods
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# to change. Because of this, you probably only want to change delegation
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# to objects of the same type as the original delegate.
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#
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# Here's an example of changing the delegation object.
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#
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# names = SimpleDelegator.new(%w{James Edward Gray II})
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# puts names[1] # => Edward
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# names.__setobj__(%w{Gavin Sinclair})
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# puts names[1] # => Sinclair
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#
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def __setobj__(obj)
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__raise__ ::ArgumentError, "cannot delegate to self" if self.equal?(obj)
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@delegate_sd_obj = obj
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end
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end
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def Delegator.delegating_block(mid) # :nodoc:
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lambda do |*args, &block|
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target = self.__getobj__
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target.__send__(mid, *args, &block)
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end.ruby2_keywords
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end
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#
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# The primary interface to this library. Use to setup delegation when defining
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# your class.
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#
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# class MyClass < DelegateClass(ClassToDelegateTo) # Step 1
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# def initialize
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# super(obj_of_ClassToDelegateTo) # Step 2
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# end
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# end
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#
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# or:
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#
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# MyClass = DelegateClass(ClassToDelegateTo) do # Step 1
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# def initialize
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# super(obj_of_ClassToDelegateTo) # Step 2
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# end
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# end
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#
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# Here's a sample of use from Tempfile which is really a File object with a
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# few special rules about storage location and when the File should be
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# deleted. That makes for an almost textbook perfect example of how to use
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# delegation.
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#
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# class Tempfile < DelegateClass(File)
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# # constant and class member data initialization...
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#
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# def initialize(basename, tmpdir=Dir::tmpdir)
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# # build up file path/name in var tmpname...
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#
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# @tmpfile = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL, 0600)
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#
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# # ...
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#
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# super(@tmpfile)
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#
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# # below this point, all methods of File are supported...
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# end
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#
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# # ...
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# end
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#
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def DelegateClass(superclass, &block)
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klass = Class.new(Delegator)
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ignores = [*::Delegator.public_api, :to_s, :inspect, :=~, :!~, :===]
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protected_instance_methods = superclass.protected_instance_methods
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protected_instance_methods -= ignores
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public_instance_methods = superclass.public_instance_methods
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public_instance_methods -= ignores
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klass.module_eval do
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def __getobj__ # :nodoc:
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unless defined?(@delegate_dc_obj)
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return yield if block_given?
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__raise__ ::ArgumentError, "not delegated"
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end
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@delegate_dc_obj
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end
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def __setobj__(obj) # :nodoc:
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__raise__ ::ArgumentError, "cannot delegate to self" if self.equal?(obj)
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@delegate_dc_obj = obj
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end
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protected_instance_methods.each do |method|
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define_method(method, Delegator.delegating_block(method))
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alias_method(method, method)
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protected method
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end
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public_instance_methods.each do |method|
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define_method(method, Delegator.delegating_block(method))
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alias_method(method, method)
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end
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end
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klass.define_singleton_method :public_instance_methods do |all=true|
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super(all) | superclass.public_instance_methods
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end
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klass.define_singleton_method :protected_instance_methods do |all=true|
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super(all) | superclass.protected_instance_methods
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end
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klass.define_singleton_method :instance_methods do |all=true|
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super(all) | superclass.instance_methods
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end
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klass.define_singleton_method :public_instance_method do |name|
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super(name)
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rescue NameError
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raise unless self.public_instance_methods.include?(name)
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superclass.public_instance_method(name)
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end
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klass.define_singleton_method :instance_method do |name|
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super(name)
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rescue NameError
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raise unless self.instance_methods.include?(name)
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superclass.instance_method(name)
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end
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klass.module_eval(&block) if block
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return klass
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end
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