diff --git a/Doc/library/operator.rst b/Doc/library/operator.rst index 9e5354f4cfc..597be9d4316 100644 --- a/Doc/library/operator.rst +++ b/Doc/library/operator.rst @@ -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: