Raymond Hettinger added the comment:
Sorry Issac, but I'm going to decline this feature request. I know you're
enthusiastic about this or some other variation but I don't think it is worthy
of becoming part of the standard library. I do encourage you to post this
somewhere as recipe (personally, I've used the ASPN cookbook to post my ideas)
or as an offering on PyPI.
Reasons:
* The use cases are thin and likely to be uncommon.
* The recipe is short and doesn't add much value.
* The anonymous or autogenerated typename is unhelpful
and the output doesn't look nice.
* It is already possible to combine a namedtuple with field
extraction using a simple lambda.
* List comprehensions are clearer, easier, and more flexible
for the task of extracting fields into a new named tuple.
* The combination of an anonymous or autogenerated typename
along with automatic field renaming will likely cause
more problems than it is worth.
* I don't expect this to mesh well with typing.NamedTuple
and the needs of static typing tools
* Debugging may become more challenging with implicitly
created named tuples that have autogenerated type names.
-- My experiments with the API ------------------------------
from collections import namedtuple
from operator import attrgetter
from pprint import pprint
def namedattrgetter (attr, *attrs):
ag = attrgetter (attr, *attrs)
if attrs:
nt = namedtuple ('_', (attr,) + attrs, rename=True)
return lambda obj: nt._make (ag (obj))
else:
return ag
Person = namedtuple('Person', ['fname', 'lname', 'age', 'email'])
FullName = namedtuple('FullName', ['lname', 'fname'])
people = [
Person('tom', 'smith', 50, 'tsm...@example.com'),
Person('sue', 'henry', 40, 'she...@example.com'),
Person('hank', 'jones', 30, 'hjo...@example.com'),
Person('meg', 'davis', 20, 'mda...@example.com'),
]
# Proposed way
pprint(list(map(namedattrgetter('lname', 'fname'), people)))
# Existing way with two-steps (attrgetter followed by nt._make)
pprint(list(map(FullName._make, map(attrgetter(*FullName._fields), people))))
# Existing way using a lambda
pprint(list(map(lambda p: FullName(p.lname, p.fname), people)))
# Best way with a plain list comprehension
pprint([FullName(p.lname, p.fname) for p in people])
----------
resolution: -> rejected
stage: -> resolved
status: open -> closed
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue31086>
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