operator module functions

Chris Kaynor ckaynor at zindagigames.com
Wed Oct 8 23:21:25 CEST 2014


On Wed, Oct 8, 2014 at 2:05 PM, Gelonida N <gelonida at gmail.com> wrote:

> On 10/8/2014 9:09 PM, Terry Reedy wrote:
>
>> On 10/8/2014 6:57 AM, Steven D'Aprano wrote:
>>
>>  According to the documentation, operator.__add__ is the "official"
>>> function,
>>> and operator.add is just there for convenience.
>>>
>>
>> You are paraphrasing "The function names are those used for special
>> class methods; variants without leading and trailing __ are also
>> provided for convenience."  But then there is the following:
>>
>> 10.3.1. Mapping Operators to Functions
>>
>> This table shows how abstract operations correspond to operator symbols
>> in the Python syntax and the functions in the operator module.
>> Operation     Syntax     Function
>> Addition     a + b     add(a, b)
>>
>> etc, using the 'convenient' names. I would like to deprecate and
>> eventually remove the dunder names.  To me, the duplication is not
>> 'convenient'.
>>
>>
>
> I'd be curious about a proposal to obsolete the double underscore
> functions and just keep operator.add or to just keep the operator +
>
> For me they seem rather distinct, though they are interchangable in
> certain situations.
>
> Perhaps I got something wrong, but all dunder functions are 'magic'
> functions. Many of them mostly should ne used when when overloading
> behaviour or when creating a class which should implement operators.
>
> print(dosomething(operator.add, 1, 2))
> print(dosomething(operator.add, a, b))


The thing being purposed to remove, is that you can also do:

print(dosomething(operator.__add__, 1, 2))
print(dosomething(operator.__add__, a, b))

Not that fact that you can define __add__ in the class, or that
"operator.add(a, b)" is the same as "a + b" (all of which are quite useful).

Basically, the operator module has a "__add__" function in addition to a
"add" function, and they are both identical (in fact, they are the same
function object):
>>> import operator
>>> operator.add
<built-in function add>
>>> operator.__add__
<built-in function add>
>>> operator.__add__ is operator.add
True
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