diff options
Diffstat (limited to 'activesupport/lib/active_support/core_ext/module/delegation.rb')
| -rw-r--r-- | activesupport/lib/active_support/core_ext/module/delegation.rb | 57 |
1 files changed, 35 insertions, 22 deletions
diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb index 6d42667e97..f855833a24 100644 --- a/activesupport/lib/active_support/core_ext/module/delegation.rb +++ b/activesupport/lib/active_support/core_ext/module/delegation.rb @@ -1,7 +1,16 @@ class Module + # Error generated by +delegate+ when a method is called on +nil+ and +allow_nil+ + # option is not used. + class DelegationError < NoMethodError; end + # Provides a +delegate+ class method to easily expose contained objects' # public methods as your own. # + # ==== Options + # * <tt>:to</tt> - Specifies the target object + # * <tt>:prefix</tt> - Prefixes the new method with the target name or a custom prefix + # * <tt>:allow_nil</tt> - if set to true, prevents a +NoMethodError+ to be raised + # # The macro receives one or more method names (specified as symbols or # strings) and the name of the target object via the <tt>:to</tt> option # (also a symbol or string). @@ -129,6 +138,8 @@ class Module # # Foo.new("Bar").name # raises NoMethodError: undefined method `name' # + # The target method must be public, otherwise it will raise +NoMethodError+. + # def delegate(*methods) options = methods.pop unless options.is_a?(Hash) && to = options[:to] @@ -164,33 +175,35 @@ class Module # # Reason is twofold: On one hand doing less calls is in general better. # On the other hand it could be that the target has side-effects, - # whereas conceptualy, from the user point of view, the delegator should + # whereas conceptually, from the user point of view, the delegator should # be doing one call. if allow_nil - module_eval(<<-EOS, file, line - 3) - def #{method_prefix}#{method}(#{definition}) # def customer_name(*args, &block) - _ = #{to} # _ = client - if !_.nil? || nil.respond_to?(:#{method}) # if !_.nil? || nil.respond_to?(:name) - _.#{method}(#{definition}) # _.name(*args, &block) - end # end - end # end - EOS + method_def = [ + "def #{method_prefix}#{method}(#{definition})", # def customer_name(*args, &block) + "_ = #{to}", # _ = client + "if !_.nil? || nil.respond_to?(:#{method})", # if !_.nil? || nil.respond_to?(:name) + " _.#{method}(#{definition})", # _.name(*args, &block) + "end", # end + "end" # end + ].join ';' else - exception = %(raise "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}") + exception = %(raise DelegationError, "#{self}##{method_prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}") - module_eval(<<-EOS, file, line - 2) - def #{method_prefix}#{method}(#{definition}) # def customer_name(*args, &block) - _ = #{to} # _ = client - _.#{method}(#{definition}) # _.name(*args, &block) - rescue NoMethodError # rescue NoMethodError - if _.nil? # if _.nil? - #{exception} # # add helpful message to the exception - else # else - raise # raise - end # end - end # end - EOS + method_def = [ + "def #{method_prefix}#{method}(#{definition})", # def customer_name(*args, &block) + " _ = #{to}", # _ = client + " _.#{method}(#{definition})", # _.name(*args, &block) + "rescue NoMethodError => e", # rescue NoMethodError => e + " if _.nil? && e.name == :#{method}", # if _.nil? && e.name == :name + " #{exception}", # # add helpful message to the exception + " else", # else + " raise", # raise + " end", # end + "end" # end + ].join ';' end + + module_eval(method_def, file, line) end end end |