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Lib/operator.py

Source:

cpython 3.14 @ ab2d84fe1023/Lib/operator.py

Lib/operator.py is the pure-Python fallback for the operator module (the C accelerator is Modules/_operator.c). It exports every Python operator as a function (operator.add, operator.mul, operator.getitem, etc.), plus the attrgetter, itemgetter, and methodcaller callable factories used for key functions in sorted and min/max.

Map​

LinesSymbolRole
1-50imports, __all__Re-export from _operator; fallback definitions
51-150Arithmetic operatorsadd, sub, mul, truediv, floordiv, mod, pow, neg, pos, abs
151-220Comparison and bitwiselt, le, eq, ne, ge, gt, and_, or_, xor, lshift, rshift
221-280Sequence operatorsgetitem, setitem, delitem, contains, concat, repeat
281-350attrgetter, itemgetter, methodcallerCallable factories

Reading​

Function wrappers​

Each operator function is a thin wrapper that calls the corresponding dunder method. The operator.add(a, b) function is equivalent to a + b; using it as a key or reducing function avoids a lambda.

# CPython: Lib/operator.py:51 add (pure-Python fallback)
def add(a, b):
    "Same as a + b."
    return a + b

The C extension _operator provides optimized C versions of these. The Python file uses try: from _operator import *; except ImportError: pass to prefer C where available.

attrgetter​

attrgetter('x.y.z') returns a callable that, when called with an object obj, evaluates obj.x.y.z. Dotted names are split on . at construction time and the getter calls getattr in a loop.

# CPython: Lib/operator.py:281 attrgetter
class attrgetter:
    def __init__(self, *attrs):
        self._attrs = attrs
        self._getters = [self._make_getter(a) for a in attrs]

    def _make_getter(self, attr):
        if '.' not in attr:
            return lambda obj: getattr(obj, attr)
        names = attr.split('.')
        def getter(obj):
            for name in names:
                obj = getattr(obj, name)
            return obj
        return getter

    def __call__(self, obj):
        if len(self._getters) == 1:
            return self._getters[0](obj)
        return tuple(g(obj) for g in self._getters)

itemgetter and methodcaller​

itemgetter(key) returns lambda obj: obj[key]. When multiple keys are given, it returns a tuple. methodcaller('name', *args, **kwargs) returns lambda obj: obj.name(*args, **kwargs). Both are used as key= arguments to sorted, min, max.

gopy notes​

Not yet ported. The planned package path is module/operator/. The arithmetic wrappers are one-liners once the Go object protocol is in place. attrgetter and itemgetter require the __getattr__ and __getitem__ protocols which are implemented in objects/protocol.go.