Issue 5191: Partial function application 'from the right' (original) (raw)

The functools module includes a 'partial' class, which allows partial function application either by positional arguments or keyword arguments. However, it cannot be used to create, for example, a function splitting a string on commas, or a function to extracts logs to base 10. I posted

http://mail.python.org/pipermail/python-dev/2009-January/085638.html

which suggested a 'partial_right' feature, such that the following would work:

import functools, math

split_comma = functools.partial_right(str.split, ',') split_comma('a,b,c') ['a', 'b', 'c']

log_10 = functools.partial_right(math.log, 10.0) log_10(100.0) 2.0

There was some useful discussion, but generally the feeling was that the extra complexity outweighed the potential benefits. Also, chained partial applications were troublesome.

The overlap in functionality between 'partial_right' and an existing patch (#1706256) to allow skipping of positional arguments was raised.

I think the present issue should probably be closed/rejected, but it was suggested on the mailing list that having the issue and patch on the record might be useful. Patches are against 2.6.1 source.