Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #19188

while True or while 1

Show key headers only | View raw

I see sometimes in other people code "while 1" instead of "while True".
I think using True is more pythonic, but I wanted to check if there is
any difference in practice.

So I tried to do the following, and the result is surprising.  For what
I can see it looks like the interpreter can optimize away the 1 boolean
conversion while it doesn't with the True, the opposite of what I
supposed.

Anyone can explain me why is that, or maybe is my conclusion wrong?

   def f1():
       while 1:
           pass

   def f2():
       while True:
           pass

   In [10]: dis.dis(f)
   2           0 SETUP_LOOP               3 (to 6)

   3 >>    3 JUMP_ABSOLUTE            3
 >>    6 LOAD_CONST               0 (None)
               9 RETURN_VALUE

   In [9]: dis.dis(f1)
   2           0 SETUP_LOOP              10 (to 13)
 >>    3 LOAD_GLOBAL              0 (True)
               6 POP_JUMP_IF_FALSE       12

   3           9 JUMP_ABSOLUTE            3
 >>   12 POP_BLOCK
 >>   13 LOAD_CONST               0 (None)
              16 RETURN_VALUE

Back to comp.lang.python | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

while True or while 1 Andrea Crotti <andrea.crotti.0@gmail.com> - 2012-01-21 13:47 +0000
  Re: while True or while 1 Erik Max Francis <max@alcyone.com> - 2012-01-21 13:14 -0800

csiph-web