Skipping execution of -with- block

Question

I am defining a context manager class and I would like to be able to skip the block of code without raising an exception if certain conditions are met during instantiation.

Answer 1

Context managers are not the right construct for this. You're asking for the body to be executed n times, in this case zero or one. If you look at the general case, n where n >= 0, you end up with a for loop:

def do_squares(n):
  for i in range(n):
    yield i ** 2

for x in do_squares(3):
  print('square: ', x)

for x in do_squares(0):
  print('this does not print')

In your case, which is more special purpose, and doesn't require binding to the loop variable:

def should_execute(mode=0):
  if mode == 0:
    yield

for _ in should_execute(0):
  print('this prints')

for _ in should_execute(1):
  print('this does not')