Difference Between Bound and Unbound Method

Question

0.00/5 (No votes)

See more:

Hello Friends,
I defined a class like below

class Robot:
	def func(self):
		self.Num = 20

on the shell i typed:

>>> print Robot.func

So i got the output like below:

<unbound method Robot.func>

Then i again typed:

>>> r = Robot()
  >> r.func.im_self.func

This time i got:

<bound method Robot.func of <__main__.Robot instance at 0x0000000002F81E48>>

If you see the outputs, you will notice a "Bound" and an "Unbound" keyword.
What is the difference between the 2?

Thanks and Regards,
Rahul

Posted 9-May-15 22:06pm

Rahul VB

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Kornfeld Eliyahu Peter · Answer 1 · 2015-05-09T23:30:00

When you call func on the class itself - Robot.func - you got a unbound object automatically created by Python...It actually means that you are executing a method without any bound to any type/instance (it is a change between 2.x and 3.x -in 2.x there was a type checking even for this type of method call...).
When you call the method on an instance you get a method call that bounded to that instance. Python translate your call of r.func to Robot.func(r), where r is the instance. In this case there is a type checking (even in 3.x) to ensure that the function and the instance are match...