On 06May2022 14:11, Loris Bennett <[email protected]> wrote:
>[email protected] (Stefan Ram) writes:
>> If you need a class, you can write a class.
>>
>> When one imports a module, the module actually gets executed.
>> That's why people write "if __name__ == '__main__':" often.
>> So, everything one wants to be done at import time can be
>> written directly into the body of one's module.
>
>So if I have a module which relies on having internal data being set
>from outside, then, even though the program only ever has one instance
>of the module, different runs, say test and production, would require
>different internal data and thus different instances. Therefore a class
>seems more appropriate and it is more obvious to me how to initialise
>the objects (e.g. by having the some main function which can read
>command-line arguments and then just pass the arguments to the
>constructor.
>
>I suppose that the decisive aspect is that my module needs
>initialisation and thus should to be a class. Your examples in the
>other posting of the modules 'math' and 'string' are different, because
>they just contain functions and no data.
Yeah, I do this quite a bit. So I might have the core class which does
it all:
class Thing:
def __init__(self, whatever...):
....
and if I'm exercising this from the command line I'll write a main
function:
def main(argv):
cmd = argv.pop(0)
... use the arguments to specify data files or modes or whatever
...
obj = Thing(...init the thing...)
obj.do_something(...)
That is usually the top thing, after the imports but before everything
else. Then right down the bottom:
if __name__ == '__main__':
sys.exit(main(sys.argv))
for running the module in command line mode:
python3 -m the.module.name args here ...
That way you can import it elsewhere for the "thing" class and also do
basic command line stuff with it directly.
Cheers,
Cameron Simpson <[email protected]>
way I'll probably write a class for a command line.
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