Class attrgetter

Lib/operator.py:240–277

Return a callable object that fetches the given attribute(s) from its operand. After f = attrgetter('name'), the call f(r) returns r.name. After g = attrgetter('name', 'date'), the call g(r) returns (r.name, r.date). After h = attrgetter('name.first', 'name.last'), the call h(r) ret

# Generalized Lookup Objects **************************************************#

class attrgetter:
    """
    Return a callable object that fetches the given attribute(s) from its operand.
    After f = attrgetter('name'), the call f(r) returns r.name.
    After g = attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).
    After h = attrgetter('name.first', 'name.last'), the call h(r) returns
    (r.name.first, r.name.last).
    """
    __slots__ = ('_attrs', '_call')

    def __init__(self, attr, /, *attrs):
        if not attrs:
            if not isinstance(attr, str):
                raise TypeError('attribute name must be a string')
            self._attrs = (attr,)
            names = attr.split('.')
            def func(obj):
                for name in names:
                    obj = getattr(obj, name)
                return obj
            self._call = func
        else:
            self._attrs = (attr,) + attrs
            getters = tuple(map(attrgetter, self._attrs))
            def func(obj):
                return tuple(getter(obj) for getter in getters)
            self._call = func

    def __call__(self, obj, /):
        return self._call(obj)

    def __repr__(self):
        return '%s.%s(%s)' % (self.__class__.__module__,
                              self.__class__.__qualname__,
                              ', '.join(map(repr, self._attrs)))

    def __reduce__(self):
        return self.__class__, self._attrs

class itemgetter:
    """