• PlexSheep@feddit.de
    15·
    11 months ago

    I mean if they can see that we type exit and show us this message, why could they not just start the exiting when we type exit?

    • Zron@lemmy.world
      202·
      11 months ago

      Because exit might be a variable you use to determine if you should exit. exit() is a function that actually does the exiting.

      It’s the difference between pointing at a jogger and saying “run” and actually running after them.

      • Bronco1676@lemmy.ml
        17·
        11 months ago

        If you have a variable called exit you’ve overwritten the function in that scope, and won’t be able to execute it.

        e.g.

        >>> exit=1
>>> exit()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable
>>>
    • WhiskyTangoFoxtrot@lemmy.world
      151·
      11 months ago

      Guessing at what the programmer wants instead of implementing consistent behaviour is what Javascript does. Do you want Python to become Javascript?

    • Bronco1676@lemmy.ml
      7·
      11 months ago

      This is the code (Github link):

      class Quitter(object):
    def __init__(self, name, eof):
        self.name = name
        self.eof = eof
    def __repr__(self):
        return 'Use %s() or %s to exit' % (self.name, self.eof)
    def __call__(self, code=None):
        # Shells like IDLE catch the SystemExit, but listen when their
        # stdin wrapper is closed.
        try:
            sys.stdin.close()
        except:
            pass
        raise SystemExit(code)

      What happens is that the python repl calls __repr__ automatically on each variable/statement that you type into the repl (except assignments e.g. x = 1). But this basically only happens in the repl. So “executing” only exit wouldn’t work in a python script as it is not calling __repr__ automatically, so better you learn how to do it right than using just exit in your python scripts and scratching your head why it works in the repl but not in your code.