venv

venv/lib/python3.12/site-packages/blinker/_utilities.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import collections.abc as c
+import inspect
+import typing as t
+from weakref import ref
+from weakref import WeakMethod
+
+T = t.TypeVar("T")
+
+
+class Symbol:
+    """A constant symbol, nicer than ``object()``. Repeated calls return the
+    same instance.
+
+    >>> Symbol('foo') is Symbol('foo')
+    True
+    >>> Symbol('foo')
+    foo
+    """
+
+    symbols: t.ClassVar[dict[str, Symbol]] = {}
+
+    def __new__(cls, name: str) -> Symbol:
+        if name in cls.symbols:
+            return cls.symbols[name]
+
+        obj = super().__new__(cls)
+        cls.symbols[name] = obj
+        return obj
+
+    def __init__(self, name: str) -> None:
+        self.name = name
+
+    def __repr__(self) -> str:
+        return self.name
+
+    def __getnewargs__(self) -> tuple[t.Any, ...]:
+        return (self.name,)
+
+
+def make_id(obj: object) -> c.Hashable:
+    """Get a stable identifier for a receiver or sender, to be used as a dict
+    key or in a set.
+    """
+    if inspect.ismethod(obj):
+        # The id of a bound method is not stable, but the id of the unbound
+        # function and instance are.
+        return id(obj.__func__), id(obj.__self__)
+
+    if isinstance(obj, (str, int)):
+        # Instances with the same value always compare equal and have the same
+        # hash, even if the id may change.
+        return obj
+
+    # Assume other types are not hashable but will always be the same instance.
+    return id(obj)
+
+
+def make_ref(obj: T, callback: c.Callable[[ref[T]], None] | None = None) -> ref[T]:
+    if inspect.ismethod(obj):
+        return WeakMethod(obj, callback)  # type: ignore[arg-type, return-value]
+
+    return ref(obj, callback)