Lib/types.py

Source:

cpython 3.14 @ ab2d84fe1023/Lib/types.py ↗

Lib/types.py collects names for built-in types that don't have dedicated builtins. Most entries are obtained by inspecting objects (type(lambda: None)) or importing from C modules.

Map

Lines	Symbol	Role
1-60	Type name bindings	FunctionType, LambdaType, CodeType, MappingProxyType, etc.
61-120	SimpleNamespace	Re-export from _collections._tuplegetter
121-200	DynamicClassAttribute	Descriptor that acts differently on class vs instance access
201-300	coroutine decorator	Wrap a generator function as a coroutine

Reading

Type collection

# CPython: Lib/types.py:18 obtaining type objects
def _f(): pass
FunctionType = type(_f)
LambdaType = type(lambda: None)   # same as FunctionType

def _g():
    yield
GeneratorType = type(_g())

async def _c(): pass
CoroutineType = type(_c())
_c().close()   # prevent ResourceWarning

These are the same type: type(lambda: None) is type(def f(): pass).

DynamicClassAttribute

# CPython: Lib/types.py:155 DynamicClassAttribute
class DynamicClassAttribute:
    def __get__(self, instance, ownerclass=None):
        if instance is None:
            # Class access: raise AttributeError to trigger __getattr__
            if self.fget is None:
                raise AttributeError()
            raise AttributeError(self.attrname)
        # Instance access: call fget
        if self.fget is None:
            raise AttributeError(...)
        return self.fget(instance)

Used by enum.Enum so that Color.name on the class triggers EnumMeta.__getattr__ (which returns the enum member named name), while Color.RED.name calls fget(instance) and returns the string 'RED'.

coroutine decorator

# CPython: Lib/types.py:230 coroutine
def coroutine(func):
    if not callable(func):
        raise TypeError(...)
    if inspect.isgeneratorfunction(func):
        # Wrap a generator function as a coroutine
        @functools.wraps(func)
        def wrapped(*args, **kwargs):
            coro = func(*args, **kwargs)
            if not isinstance(coro, _GeneratorWrapper):
                coro = _GeneratorWrapper(coro)
            return coro
        return wrapped
    ...

types.coroutine is used in the old asyncio compatibility layer. Modern code uses async def.

gopy notes

types module is in module/types/. FunctionType, CodeType, ModuleType etc. are the types already defined in objects/. MappingProxyType wraps objects/mapping_proxy.go. SimpleNamespace is objects/namespace.go. DynamicClassAttribute is needed by enum (used by http.HTTPStatus and similar).