On Sun, Jan 31, 2016 at 7:19 AM, <c.bu...@posteo.jp> wrote:
> I am not sure what the problem is here, so I don't really know how I
> should call the subject for that question. Please offer a better
> subject.
>
> The code below is a extrem simplified example of the original one. But
> it reproduce the problem very nice. Please focus on the variable
> `return_code`.
>
> There is a `list()` of numbers without the number `7` in. The code
> check if the number `7` is in and should tell that it is not in. But it
> does tell me that `7 is in`. ;)
>
> I think I didn't know some special things about scopes of variables in
> Python. This might be a very good problem to learn more about that. But
> I don't know on which Python topic I should focus here to find a
> solution for my own.
>
> #!/usr/bin/env python3
> import sys
>
> def walkOn_ids(ids, handlerFunction, **handlerArgs):
> for one_id in ids:
> handlerFunction(one_id=one_id, **handlerArgs)
> print('after handler-call for id {}\t{}'
> .format(one_id, handlerArgs))
>
> def _on_id(one_id, return_code):
> if return_code is False:
> return
>
The above returns None, not False. Maybe you want False, so return False.
However, when you call this function below, you set return_code = True, so
it will never be False
>
> if one_id == 7:
> return_code = True
> else:
> return_code = False
>
The above could be just:
return one_id == 7
no need for if/else
>
> print('one_id: {}\treturn_code: {}'.format(one_id, return_code))
>
>
> def _isSevenInIt(ids):
> return_code = True
>
> walkOn_ids(ids=ids,
> handlerFunction=_on_id,
> return_code=return_code)
>
> return return_code
>
This will always return True because you set return_code = True and never
change it. You might want this:
return_code = walkOn_ids(...
>
>
> ids = [1,2,3,4,5,6,8,9] # NO 7
> print(ids)
>
> if _isSevenInIt(ids) is True:
> print('7 is in')
> else:
> print('no 7 in it')
>
> sys.exit()
>
> Of course I could make `return_code` a `global` variable. But that is
> not the goal. The goal is to carry this variable inside the
> walker-function and bring the result back. In the original code I will
> use some more complexe data structures with `**handlerArgs`.
>
Before you start randomly making variables global, make sure you have
written code that does what you want it to. Globals to fix bad coding will
quickly bring a big mess. Of course its more subtle than this, but mostly
globals are a very bad idea.
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> https://mail.python.org/mailman/listinfo/python-list
>
--
Joel Goldstick
http://joelgoldstick.com/stats/birthdays
--
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