bpo-32380: Create functools.singledispatchmethod (#6306)
diff --git a/Lib/functools.py b/Lib/functools.py
index c8b79c2..d5f4393 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -11,7 +11,7 @@
__all__ = ['update_wrapper', 'wraps', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES',
'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial',
- 'partialmethod', 'singledispatch']
+ 'partialmethod', 'singledispatch', 'singledispatchmethod']
try:
from _functools import reduce
@@ -826,3 +826,40 @@
wrapper._clear_cache = dispatch_cache.clear
update_wrapper(wrapper, func)
return wrapper
+
+
+# Descriptor version
+class singledispatchmethod:
+ """Single-dispatch generic method descriptor.
+
+ Supports wrapping existing descriptors and handles non-descriptor
+ callables as instance methods.
+ """
+
+ def __init__(self, func):
+ if not callable(func) and not hasattr(func, "__get__"):
+ raise TypeError(f"{func!r} is not callable or a descriptor")
+
+ self.dispatcher = singledispatch(func)
+ self.func = func
+
+ def register(self, cls, method=None):
+ """generic_method.register(cls, func) -> func
+
+ Registers a new implementation for the given *cls* on a *generic_method*.
+ """
+ return self.dispatcher.register(cls, func=method)
+
+ def __get__(self, obj, cls):
+ def _method(*args, **kwargs):
+ method = self.dispatcher.dispatch(args[0].__class__)
+ return method.__get__(obj, cls)(*args, **kwargs)
+
+ _method.__isabstractmethod__ = self.__isabstractmethod__
+ _method.register = self.register
+ update_wrapper(_method, self.func)
+ return _method
+
+ @property
+ def __isabstractmethod__(self):
+ return getattr(self.func, '__isabstractmethod__', False)