Merge pull request #148 from pallets-eco/ident

restore identity handling for str and int senders

CHANGES.rst

@@ -3,6 +3,8 @@ Version 1.8.1
 
 Unreleased
 
+-   Restore identity handling for ``str`` and ``int`` senders. :pr:`148`
+
 
 Version 1.8.0
 -------------

src/blinker/_utilities.py

@@ -39,9 +39,20 @@ def __getnewargs__(self) -> tuple[t.Any]:
 
 
 def make_id(obj: object) -> t.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)
 
 

tests/test_signals.py

@@ -485,15 +485,15 @@ def values_are_empty_sets_(dictionary: dict[t.Any, t.Any]) -> None:
 
 
 def test_int_sender() -> None:
-    sentinel = []
+    count = 0
 
     def received(sender: t.Any) -> None:
-        sentinel.append(sender)
+        nonlocal count
+        count += 1
 
     sig = blinker.Signal()
-
     sig.connect(received, sender=123456789)
-    sig.send(123456789)
-    assert len(sentinel) == 1
-    sig.send(123456789 + 0)  # Forces a new id with CPython
-    assert len(sentinel) == 2
+    sig.send(123456789)  # Python compiler uses same instance for same literal value.
+    assert count == 1
+    sig.send(int("123456789"))  # Force different instance with same value.
+    assert count == 2