[docs] Issue with python function names

Georg Brandl georg at python.org
Sun Feb 7 05:43:06 EST 2016

Hash: SHA1

Hi David,

there are few reasons why this is the way it is:

- - The builtins are not the only names that can be accidentally overridden.
  The same goes for imported modules, or any classes/functions imported
  from modules.  It's hard to see where to draw the line.

- - At the same time, being able to override existing name bindings is part
  of the Pythonic "consenting adults" policy.  It makes it possible, for
  example, to quickly change how output using "print" works in a script.

- - The interactive shell is a special case anyway.  Normally the shadowing
  is limited to the module or local scope where it happens.

Note that as with many other questions of freedom vs enforcement, linters
like pyflakes/pylint do a good job of recoginizing this shadowing and
warning about it if so desired.


On 02/06/2016 06:49 AM, david becker wrote:
> And of course the same thing happens if we use them for variable names as
> well.
>>>> type = 2 type(4)
> Traceback (most recent call last): File "<pyshell#74>", line 1, in
> <module> type(4) TypeError: 'int' object is not callable
> I feel there is no point in allowing them as they cannot be used. Users
> are restricted to use the 32 keywords but we can't force them to remember
> all built in function names and not to use them as variable or function
> names. :)
> Thanks, David Becker
> On Sat, Feb 6, 2016 at 11:11 AM, david becker <ardavidbecker at gmail.com 
> <mailto:ardavidbecker at gmail.com>> wrote:
> Hi,
> I have a query in using function names. Python allows users to write their 
> own functions with built-in function names.
> Example: def print(): return "strange"
> print() -- Returns strange ++++++++++++++++++++++++++++
> But the built in "print" function doesn't work any more till i restart the 
> shell. I personally feel users should not be allowed to use built in
> function names. Is there any special reason why python allows them?
> Thanks, David Becker
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