Question

Dive into Python –

It would be tempting but incorrect to
call this the constructor of the
class. It’s tempting, because it looks
like a constructor (by convention,
__init__ is the first method defined for the class), acts like one (it’s
the first piece of code executed in a
newly created instance of the class),
and even sounds like one (“init”
certainly suggests a constructor-ish
nature). Incorrect, because the object
has already been constructed by the
time __init__ is called, and you
already have a valid reference to the
new instance of the class.

Quote suggests it is incorrect to call __init__ as a constructor because the object is already constructed by the time __init__ is called. But! I have always been under the impression that the constructor is called only after the object is constructed because it is essentially used to initialized the data members of the instance which wouldn’t make sense if the object didn’t exist by the time constructor was called? (coming from C++/Java background)

Answer 1

If you have a class Foo then:

• Foo() is the constructor
• Foo.__init__() is the initializer
• Foo.__new__() is the allocator

Construction of a Python object is simply allocation of a new instance followed by initialization of said instance.