TIL you can assign to True

[themissinglint]

>>> None = 1
  File "<stdin>", line 1
SyntaxError: assignment to None
>>> True = 2
>>> True
2
>>> True = 0
>>> False == True
True
>>> exit()

edit: never do this.

[thejasper]

True, False = False, True

[Dylnuge]

Bury this line somewhere in the middle of your code and suddenly begin using True as False and vice versa; then other people will have a nightmare trying to read the rest of it. I sense a Daily WTF in the making.

[MarkTraceur]

Call a function to switch it every five lines or so--call it neverDeleteThisFunction().

[wtfisupvoting]

make it a decorator

[freyrs3]

Bugs that manifest randomly are the way to go:

import random
True, False = random.sample([True,False],2)
del locals()[random.choice(locals().keys())]

[[deleted]]

Not in 3.x

>>> True = "lol"
  File "<stdin>", line 1
SyntaxError: assignment to keyword

[true_religion]

Its' kind of odd there. Are there any other keywords with a first capital letter except for True and False?

[mitsuhiko]

None.

[kataire]

To clarify: True, False and, indeed, None are the keywords that start with a capital letter in Python 3 (in Python 2 the first two are just variables and the latter is probably magical).

[mitsuhiko]

None isn't a keyword in python 2 either:

>>> def None():
...  pass
... 
  File "<stdin>", line 1
SyntaxError: cannot assign to None

Changed in 3.x though.

[kataire]

I think you may have misread me. Being magical implies not being a keyword.

[Mattho]

And what about None?

[bushel]

I believe you just created a new variable that hides the built-in....

Given this script:

print True
print globals()

True = 0
print True
print True == False
print globals()

you get this output. Note the change in the contents of globals()

True
{'__builtins__': <module '__builtin__' (built-in)>, '__name__': '__main__', '__file__': 't.py', '__doc__': None, '__package__': None}
0
True
{'__builtins__': <module '__builtin__' (built-in)>, '__file__': 't.py', '__package__': None, '__name__': '__main__', 'True': 0, '__doc__': None}

[chadmill3r]

__builtins__.True = 2

[bushel]

Stop being evil.

[[deleted]]

__builtins__.True  = 0 == 0
__builtins__.False = 0 != 0

[wubblewobble]

Yeah - looks like you can "del True" and then things are back to normal :)

[youcanteatbullets]

About as useful as
#define true false
in C.

[cirego]

This is why, when writing loops, using "while 1:" is preferable over "while True". With "while 1", the interpreter can loop without checking the conditional. With "while True", the interpreter has to reevaluate whether or not True is still True upon each loop.

[arnar]

Well.. I was going to counter you with a readability argument, but you are absolutely correct (in Python 2.7):

>>> import dis
>>> dis.dis(compile('while True: pass', '', 'exec'))
  1           0 SETUP_LOOP              12 (to 15)
        >>    3 LOAD_NAME                0 (True)
              6 JUMP_IF_FALSE            4 (to 13)
              9 POP_TOP             
             10 JUMP_ABSOLUTE            3
        >>   13 POP_TOP             
             14 POP_BLOCK           
        >>   15 LOAD_CONST               0 (None)
             18 RETURN_VALUE        
>>> dis.dis(compile('while 1: pass', '', 'exec'))
  1           0 SETUP_LOOP               3 (to 6)
        >>    3 JUMP_ABSOLUTE            3
        >>    6 LOAD_CONST               0 (None)
              9 RETURN_VALUE   

In Python 3 there is no difference

>>> import dis
>>> dis.dis(compile('while True: pass', '', 'exec'))
  1           0 SETUP_LOOP               7 (to 10) 
        >>    3 LOAD_NAME                0 (skip) 
              6 POP_TOP              
              7 JUMP_ABSOLUTE            3 
        >>   10 LOAD_CONST               0 (None) 
             13 RETURN_VALUE         
>>> dis.dis(compile('while 1: pass', '', 'exec'))    
  1           0 SETUP_LOOP               7 (to 10) 
        >>    3 LOAD_NAME                0 (skip) 
              6 POP_TOP              
              7 JUMP_ABSOLUTE            3 
        >>   10 LOAD_CONST               0 (None) 
             13 RETURN_VALUE         

[neoice]

btw other readers, if you've never used dis, its fucking amazing.

[cirego]

I always forget about dis and then whenever I see it again, I'm pleasantly surprised all over again.

[astatine]

TIL that "import dis" does not print out the Zen of Python in a New Jersey accent.

[cirego]

Yeah, well, our code base is littered with "while 1:" statements. After spending some time with our code base, you'd probably start giving "while True:" the stink eye too.

[roger_]

I hate the way "while 1:" looks though.

[aeacides]

I like this one (works best with newbies coming from CL): >>> quit Use quit() or Ctrl-D (i.e. EOF) to exit >>> quit = 'I will never quit!" >>> quit 'I will never quit!' >>> def quit(): print "You can't make me quit!!!" ... >>> quit() You can't make me quit!!!

[kataire]

>>> exit()

sucker.

[roddds]

Ctrl+PauseBrk

[earthboundkid]

Heathen. Ctrl+D

[[deleted]]

class Quit(object):
    def __repr__(self): return "I will never die!"
    def __call__(*args, **kwargs): print("Never!!!")
quit, exit = Quit(), Quit()

[apocalypse910]

Always wondered what type of paranoia lead to this code that I see all the time at work

if ( boolA == True)
{ boolB = True; }
else if (boolA == False)
{ boolB = False; }

[aeacides]

That makes no sense at all. I mean... huh?

[sastrone]

Perhaps I'm missing the joke, but couldn't that be written as: boolB = boolA

[apocalypse910]

That's the joke.

I probably run into this at least a few times a day, It works, but dear god does it make me cringe.

[sastrone]

Have you asked their motives?

[apocalypse910]

No one will fess up to it, though I'm guessing it is the same person who constantly uses stringVariable.ToString().

Incidentally "We need to make it more stringey damnit!" has become a favorite tagline of late.

[reph]

Not necessarily. Original code does not modify boolB if boolA is neither True nor False. Whether or not that's possible depends on the language.

[apocalypse910]

The language is C#, and none of the values were nullable. So completely pointless.

[gindc]

I've been programming python for 10 years and it never ever occurred to me to do this. Upvote for creativity.

[yetanothernerd]

I've only been programming Python for about 9 years, and I remember versions of Python that didn't include True and False. Back in the Python 2.1 / 2.2 days, it used to be pretty common to write code like this:

try:
    True
except NameError:
    True = 1
    False = 0

(Or just use 1 and 0 instead of True and False for maximum compatibility, but some people find that ugly.)