Isaac Morland added the comment:
I've attached a file which illustrates what I'm proposing to happen with the
examples from the help. Note that attrgetter (attr) is not affected, only
attrgetter (*attrs) for more than one attribute. The idea is that tuples
resulting from attrgetter functions will retain the attribute names from the
original object. In some work I have done recently this would have been very
handy with groupby.
I had some initial confusion because changing the Python attrgetter
implementation didn't make any difference. Once I realized I needed to turn
off import of the C implementation, I figured the rest out fairly quickly.
Here is the diff:
diff --git a/Lib/operator.py b/Lib/operator.py
index 0e2e53e..9b2a8fa 100644
--- a/Lib/operator.py
+++ b/Lib/operator.py
@@ -247,8 +247,12 @@ class attrgetter:
else:
self._attrs = (attr,) + attrs
getters = tuple(map(attrgetter, self._attrs))
+
+ from collections import namedtuple
+ nt = namedtuple ('attrgetter', self._attrs, rename=True)
+
def func(obj):
- return tuple(getter(obj) for getter in getters)
+ return nt._make (getter(obj) for getter in getters)
self._call = func
def __call__(self, obj):
@@ -409,7 +413,7 @@ def ixor(a, b):
try:
- from _operator import *
+ pass
except ImportError:
pass
else:
There are some issues that still need to be addressed. The biggest is that
I've turned off the C implementation. I assume that we'll need a C
implementation the new version. In addition to this:
1) I just call the namedtuple type "attrgetter". I'm thinking something
obtained by mashing together the field names or something similar might be more
appropriate. However, I would prefer not to repeat the logic within namedtuple
that deals with field names that aren't identifiers. So I'm wondering if maybe
I should also modify namedtuple to allow None as the type name, in which case
it would use an appropriate default type name based on the field names.
2) I import from collections inside the function. It didn't seem to work at
the top-level, I'm guessing because I'm in the library and collections isn't
ready when operator is initialized. This may be fine I just point it out as
something on which I could use advice.
I'm hoping this provides enough detail for people to understand what I'm
proposing and evaluate whether this is a desireable enhancement. If so, I'll
dig into the C implementation next, although I may need assistance with that.
----------
Added file: http://bugs.python.org/file46791/test_attrgetter.py
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<http://bugs.python.org/issue30020>
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