Why is 'init' not assignable?

Question

I just read that the init method can't be used as a value. Meaning:

var x = SomeClass.someClassFunction // ok
var y = SomeClass.init              // error

Example found on Language reference

Why should it be like that? Is it a way to enforce language level that too dirty tricks come into place, because of some cohertion or maybe because it interferes with another feature?

Answer 1

Unlike Obj-C, where the init function can be called multiple times without problems, in Swift there actually is no method called init.

init is just a keyword meaning "the following is a constructor". The constructor is called always via MyClass() during the creation of a new instance. It's never called separately as a method myInstance.init(). You can't get a reference to the underlying function because it would be impossible to call it.

This is also connected with the fact that constructors cannot be inherited. Code

var y = SomeClass.init

would also break subtyping because the subtypes are not required to have the same initializers.