[Python-ideas] A macro for easier rich comparisons

[Petr Viktorin]

On Wed, Mar 18, 2015 at 12:01 PM, M.-A. Lemburg <mal at egenix.com> wrote:
> On 18.03.2015 11:53, Petr Viktorin wrote:
>> ...
>> I propose adding a public macro to ease this. My version takes two C-orderable values and the
>> operation, similar to richcmpfunc:
>>
>> #define Py_RICHCOMPARE(val1, val2, op) ( \
>>     ((op) == Py_EQ) ? PyBool_FromLong((val1) == (val2)) : \
>>     ((op) == Py_NE) ? PyBool_FromLong((val1) != (val2)) : \
>>     ((op) == Py_LT) ? PyBool_FromLong((val1) < (val2)) : \
>>     ((op) == Py_GT) ? PyBool_FromLong((val1) > (val2)) : \
>>     ((op) == Py_LE) ? PyBool_FromLong((val1) <= (val2)) : \
>>     ((op) == Py_GE) ? PyBool_FromLong((val1) >= (val2)) : \
>>     (Py_INCREF(Py_NotImplemented), Py_NotImplemented))
>>
>> (As for the behavior for unknown op: for most cases the best thing to do is setting an error and
>> returning NULL, but that doesn't fit into a macro. A surprising number of richcmpfunc's in CPython
>> either return NULL without error (e.g. tupleobject), or fall through and return True/False
>> arbitrarily (as in bytearrayobject). Datetime does an assert.
>> I think Py_NotImplemented is a good value to return)
>> ...
>> Is this a PEP-worthy idea?
>
> This is a great idea, no need for a PEP :-) Please submit the patch on
> the bug tracker and also include a patch for the C API documentation.

Issue with patches is here: http://bugs.python.org/issue23699