Is the initialize method a built-in method in Ruby?
Why do we have to pass arguments when we create a new object, and why it goes directly to that initialize method? And, can we create a class without an initialize method?
2 Answers
You can consider the relationship between the Class#new method and each class's #initialize method to be implemented more or less like this:
class Class
def new
instance = allocate()
instance.initialize
return instance
end
end
class Foo
def initialize
# Do nothing
end
end
You can create a class without explicitly defining an #initialize method, because the #initialize method is defined by default to do nothing, and its return value is always ignored (regardless of what value you return).
The arguments you pass to Class#new are always passed directly to #initialize in the same order and format. For example:
class Class
def new (arg1, arg2, &block_arg)
instance = allocate()
instance.initialize(arg1, arg2, &block_arg)
return instance
end
end
class MyClass
def initialize (arg1, arg2, &block_arg)
# Do something with args
end
end
Comments
The logic behind creating new objects consists of two elements. First, you need to create a new object within the memory. This is done by calling allocate method on given class (it is defined on a Class class) - it takes no parameters and its only responsibility is to get a free slot from ruby memory heap slab, place a new object in that spot and return the object. The second step is to call initialize method on this newly created object - this is why initialize is an instance method rather then a class method.
The default initialize method is part of the language and it literally does nothing and takes no params.
new method is just a handy shorthand which first calls the allocate method, and then calls the initialize method (with all the passed params) on the object returned by the allocate method.
initialize: What do you mean by built in? It's a [constructor[(en.wikipedia.org/wiki/Constructor_(object-oriented_programming)): used for creating instances of a class. It's not compulsory to pass arguments toinitialize. can we create a class without an initialize method: yes