Ruby Language Classes New, allocate, and initialize
Example
In many languages, new instances of a class are created using a special new keyword. In Ruby, new is also used to create instances of a class, but it isn't a keyword; instead, it's a static/class method, no different from any other static/class method. The definition is roughly this:
class MyClass
def self.new(*args)
obj = allocate
obj.initialize(*args) # oversimplied; initialize is actually private
obj
end
end
allocate performs the real 'magic' of creating an uninitialized instance of the class
Note also that the return value of initialize is discarded, and obj is returned instead. This makes it immediately clear why you can code your initialize method without worrying about returning self at the end.
The 'normal' new method that all classes get from Class works as above, but it's possible to redefine it however you like, or to define alternatives that work differently. For example:
class MyClass
def self.extraNew(*args)
obj = allocate
obj.pre_initialize(:foo)
obj.initialize(*args)
obj.post_initialize(:bar)
obj
end
end
