classQuitter(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:
passraise 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.
“exit”
✈️: Use exit() or Ctrl-D (I.e. EOF) to exit
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?
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.
If you have a variable called
exityou’ve overwritten the function in that scope, and won’t be able to execute it.e.g.
Reminds me of setting pi = 3 in my friends matlab subroutines in school.
wow it does do that. cool
Guessing at what the programmer wants instead of implementing consistent behaviour is what Javascript does. Do you want Python to become Javascript?
Just once I want
'1' + '2'to equal'3'. Is that so much to ask?You want to remove the string concatenation operator? Cause that’ll do it
I think every language needs a
pleaseoperator, which acts to enforce human expectation of a statement:'1' + '1' ## evaluates to '11' please '1' + '1' ## evaluates to '2'I kinda like that
Yes. Yes it is.
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” onlyexitwouldn’t work in a python script as it is not calling__repr__automatically, so better you learn how to do it right than using justexitin your python scripts and scratching your head why it works in the repl but not in your code.Because python has strong opinions