Check if variable is an instance of a File object
Marc 'BlackJack' Rintsch
bj_666 at gmx.net
Fri Sep 15 03:51:11 EDT 2006
In <1158304694.673361.62600 at b28g2000cwb.googlegroups.com>, sc_wizard29
wrote:
> Maybe these questions will sound strange to you, but I sometime have a
> hard time switching from Java to Python ;-)
>
> Let's say I have a function like this :
>
> def show_lines(file):
> for next_line in file:
> ...
>
> What can I do to be sure that the input argument is indeed a 'File'
> object ?
Why do you want to be sure? I would even rename the argument:
def show_lines(lines):
for line in lines:
...
This works with *every* iterable that contains "lines". No need to
"cripple" it with a type checking.
> #2 : should I do nothing ? (but I don't like the idea of risking to
> have a runtime exception raised somewhere)
Then don't use Python. Except `SyntaxError` almost every
exception is a runtime one.
And what do you do if you check for `file` and it isn't such an instance?
Raise an exception? A no, that's something you don't like. So what else? ;-)
Ciao,
Marc 'BlackJack' Rintsch
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