Method summary from 3/13/13

[Cynthia Kiser]

Sorry, I meant to post these last week after class. These are the notes from our whiteboard summary of the first half of Metaprogramming Ruby.

define_method: dynamically create method using blocks - within some specific scope

class_eval (aka module_eval): Use when you want into a class but you can't reopen the class either because you don't kn\

ow the class name yet, or because you don't want to change scope

instance_eval: opens an object and executes code in the object's scope

Kernal#eval(string): evaluates its argument (which is usually a string of code)

Object#send(:method_name, args) (e.g. my_thing.send(:method_name, args)): Calls method_name on object, passing in the a\

rguments, args.

method_missing(name, args, &block): dynamically creates a method when you call a method that does not exist in this obj\

ect or its inheritance tree.

instance_variable_set: sets an instance variable dynamically (use this when you don't know the name of the instance var\

iable until run time.

instance_variable_get: returns an instance variable dynamically (use this when you don't know the name of the instance \

variable until run time.

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def self.inherited(base) ...... end : when base inherits from self, run this method

def self.included(base) ..... end : runs the code in this method when self is included into another object

def self.include(*modules) ...... end : run this code when you include the modules on the list; REMEMBER to call super.

object.include(ModuleName): add ModuleName's methods as the object's instance methods.

object.extend(ModuleName): add ModuleName's methods that go into object's eigenclass.

                   Same as: class << self

                              include ModuleName

                            end