provide sample implementations for attrgetter and methodcaller

This commit is contained in:
Benjamin Peterson 2010-08-21 20:08:36 +00:00
parent c16f8b33e0
commit 2d55e2aab3
1 changed files with 23 additions and 2 deletions

View File

@ -333,7 +333,23 @@ expect a function argument.
attribute is requested, returns a tuple of attributes. After,
``f = attrgetter('name')``, the call ``f(b)`` returns ``b.name``. After,
``f = attrgetter('name', 'date')``, the call ``f(b)`` returns ``(b.name,
b.date)``.
b.date)``. Equivalent to::
def attrgetter(*items):
if len(items) == 1:
attr = items[0]
def g(obj):
return resolve_attr(obj, attr)
else:
def g(obj):
return tuple(resolve_att(obj, attr) for attr in items)
return g
def resolve_attr(obj, attr):
for name in attr.split("."):
obj = getattr(obj, name)
return obj
The attribute names can also contain dots; after ``f = attrgetter('date.month')``,
the call ``f(b)`` returns ``b.date.month``.
@ -383,7 +399,12 @@ expect a function argument.
additional arguments and/or keyword arguments are given, they will be given
to the method as well. After ``f = methodcaller('name')``, the call ``f(b)``
returns ``b.name()``. After ``f = methodcaller('name', 'foo', bar=1)``, the
call ``f(b)`` returns ``b.name('foo', bar=1)``.
call ``f(b)`` returns ``b.name('foo', bar=1)``. Equivalent to::
def methodcaller(name, *args, **kwargs):
def caller(obj):
return getattr(obj, name)(*args, **kwargs)
return caller
.. _operator-map: