1st Version

.venv/lib/python3.10/site-packages/blinker/_utilities.py

@@ -0,0 +1,105 @@
+from __future__ import annotations
+
+import typing as t
+from weakref import ref
+
+from blinker._saferef import BoundMethodWeakref
+
+IdentityType = t.Union[t.Tuple[int, int], str, int]
+
+
+class _symbol:
+    def __init__(self, name):
+        """Construct a new named symbol."""
+        self.__name__ = self.name = name
+
+    def __reduce__(self):
+        return symbol, (self.name,)
+
+    def __repr__(self):
+        return self.name
+
+
+_symbol.__name__ = "symbol"
+
+
+class symbol:
+    """A constant symbol.
+
+    >>> symbol('foo') is symbol('foo')
+    True
+    >>> symbol('foo')
+    foo
+
+    A slight refinement of the MAGICCOOKIE=object() pattern.  The primary
+    advantage of symbol() is its repr().  They are also singletons.
+
+    Repeated calls of symbol('name') will all return the same instance.
+
+    """
+
+    symbols = {}  # type: ignore[var-annotated]
+
+    def __new__(cls, name):
+        try:
+            return cls.symbols[name]
+        except KeyError:
+            return cls.symbols.setdefault(name, _symbol(name))
+
+
+def hashable_identity(obj: object) -> IdentityType:
+    if hasattr(obj, "__func__"):
+        return (id(obj.__func__), id(obj.__self__))  # type: ignore[attr-defined]
+    elif hasattr(obj, "im_func"):
+        return (id(obj.im_func), id(obj.im_self))  # type: ignore[attr-defined]
+    elif isinstance(obj, (int, str)):
+        return obj
+    else:
+        return id(obj)
+
+
+WeakTypes = (ref, BoundMethodWeakref)
+
+
+class annotatable_weakref(ref):
+    """A weakref.ref that supports custom instance attributes."""
+
+    receiver_id: t.Optional[IdentityType]
+    sender_id: t.Optional[IdentityType]
+
+
+def reference(  # type: ignore[no-untyped-def]
+    object, callback=None, **annotations
+) -> annotatable_weakref:
+    """Return an annotated weak ref."""
+    if callable(object):
+        weak = callable_reference(object, callback)
+    else:
+        weak = annotatable_weakref(object, callback)
+    for key, value in annotations.items():
+        setattr(weak, key, value)
+    return weak  # type: ignore[no-any-return]
+
+
+def callable_reference(object, callback=None):
+    """Return an annotated weak ref, supporting bound instance methods."""
+    if hasattr(object, "im_self") and object.im_self is not None:
+        return BoundMethodWeakref(target=object, on_delete=callback)
+    elif hasattr(object, "__self__") and object.__self__ is not None:
+        return BoundMethodWeakref(target=object, on_delete=callback)
+    return annotatable_weakref(object, callback)
+
+
+class lazy_property:
+    """A @property that is only evaluated once."""
+
+    def __init__(self, deferred):
+        self._deferred = deferred
+        self.__doc__ = deferred.__doc__
+
+    def __get__(self, obj, cls):
+        if obj is None:
+            return self
+        value = self._deferred(obj)
+        setattr(obj, self._deferred.__name__, value)
+        return value