[Python-ideas] PEP proposal: unifying function/method classes

[Erik Bray]

On Fri, Mar 23, 2018 at 11:25 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Fri, 23 Mar 2018 07:25:33 +0100
> Jeroen Demeyer <J.Demeyer at UGent.be> wrote:
>
>> On 2018-03-23 00:36, Antoine Pitrou wrote:
>> > It does make sense, since the proposal sounds ambitious (and perhaps
>> > impossible without breaking compatibility).
>>
>> Well, *some* breakage of backwards compatibility will be unavoidable.
>>
>>
>> My plan (just a plan for now!) is to preserve backwards compatibility in
>> the following ways:
>>
>> * Existing Python attributes of functions/methods should continue to
>> exist and behave the same
>>
>> * The inspect module should give the same results as now (by changing
>> the implementation of some of the functions in inspect to match the new
>> classes)
>>
>> * Everything from the documented Python/C API.
>>
>>
>> This means that I might break compatibility in the following ways:
>>
>> * Changing the classes of functions/methods (this is the whole point of
>> this PEP). So anything involving isinstance() checks might break.
>>
>> * The undocumented parts of the Python/C API, in particular the C structure.
>
> One breaking change would be to add __get__ to C functions.  This means
> e.g. the following:
>
> class MyClass:
>     my_open = open
>
> would make my_open a MyClass method, therefore you would need to spell
> it:
>
> class MyClass:
>     my_open = staticmethod(open)
>
> ... if you wanted MyClass().my_open('some file') to continue to work.
>
> Of course that might be considered a minor annoyance.

I don't really see your point in this example.  For one: why would
anyone do this?  Is this based on a real example?  2) That's how any
function works.  If you put some arbitrary function in a class body,
and it's not able to accept an instance of that class as its first
argument, then it will always be broken unless you make it a
staticmethod.  I don't see how there should be any difference there if
the function were implemented in Python or in C.

Thanks,
E