[Python-ideas] Bug? Feature? setattr(foo, '3', 4) works!

[Cem Karan]

On Dec 19, 2014, at 6:11 AM, Chris Angelico <rosuav at gmail.com> wrote:

> On Fri, Dec 19, 2014 at 10:00 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>> Most implementations will go with whichever is faster in their particular
>> case (for CPython, that means using the standard permissive dict type, for
>> Jython, it means only allowing strings, for other implementations, I'm not
>> sure).
> 
> What do you mean by "only allowing strings"? CPython doesn't allow
> non-string attributes, and Jython does allow non-identifier
> attributes:
> 
> Jython 2.5.3 (, Oct 8 2014, 03:39:09)
> [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_65
> Type "help", "copyright", "credits" or "license" for more information.
>>>> class x(object): pass
> ...
>>>> x=x()
>>>> setattr(x,"1","2")
>>>> getattr(x,"1")
> '2'
>>>> setattr(x,1,2)
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
> TypeError: setattr(): attribute name must be string
> 
> Python 3.5.0a0 (default:64e45efdc3e2, Dec 11 2014, 11:52:01)
> [GCC 4.7.2] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> class x: pass
> ...
>>>> x=x()
>>>> setattr(x,"1",2)
>>>> getattr(x,"1")
> 2
>>>> setattr(x,1,2)
> Traceback (most recent call last):
>  File "<stdin>", line 1, in <module>
> TypeError: attribute name must be string, not 'int'
> 
> 
> (I'm not sure why there's the empty string in the Jython version tag;
> this is what I got by apt-getting jython on Debian Jessie.)
> 
> In any case, it's probably time this moved off python-ideas.

What's the best place to move it to?  If this is a bug, I'll write up a bug report, but if this is a change in the language definition, then it might be best to keep it here.

Thanks,
Cem Karan