Python 2.4: Why only assignments to None are forbiden?
jmeile at hotmail.com
Fri Nov 12 22:11:59 CET 2004
Textually from the highlights of python 2.4:
"Assigning to None - the compiler now treats assigning to None as a
I think in general assignments to built-in types, functions, and
variables should be also forbiden. It's a common mistake to do things
>>> def getFileName(file):
... return parts('/')[-1]
Specially if you come from python 2.1.x where "file" didn't exist.
Instead, there was "open"
On the example's context, file is a string and won't cause any damage
because it is inside a function, so, the scope is local and it will be
deleted after the function call. But think what would happen if somebody
defines "file" as a global variable and other people use that code? For
the author won't be any consequences at all, because if s/he does this,
it means that probably s/he isn't working with files, but if somebody
else takes that code and doesn't see this, then s/he will invest some
time trying to find the bug.
Doing this validation for python 2.4.x will break some things, like the
validation with "None" does. But I think it's better when you now that
you are trying to use a "reserved word", you could as well use the "str"
as an example, which I think is also common on newies.
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