How to use the pass statement in Python

Question

I am in the process of learning Python and I have reached the section about the pass statement. The guide I'm using defines it as being a Null statement that is commonly used as a placeholder.

I still don't fully understand what that means though. Can someone show me a simple/basic situation where the pass statement would be used and why it is needed?

Answer 1

Let me give you an example, you are designing a new class with some methods that you don't want to implement, yet.

class MyClass(object):
   def meth_a(self):
       pass
   def meth_b(self):
       print "I'm meth_b"

If you would leave out the pass, the code wouldn't run.

You would then get an

IndentationError: expected an indented block

To summarize, the pass statement does nothing particular but can act as a placeholder, as shown before.

Answer 2

In Python programming, pass is a null statement. The difference between a comment and pass statement in Python is that, while the interpreter ignores a comment entirely, pass is not ignored.

example

for letter in 'python':
   if letter == 'h':
      pass
      print 'This is pass block'
   print 'Current Letter :', letter

print "Good bye!"

output:

   current letter : P 

 current letter : y 

current letter : t 

This is pass block 

current letter : h 

current letter : o 

current letter : n

 Good bye!