add unbind_threadlocal and try_unbind_threadlocal methods (#239)

* add unbind_threadlocal and try_unbind_threadlocal methods for "new" threadlocal context

* match threadlocal.unbind to contextvars.unbind behavior

Co-authored-by: Hynek Schlawack <[email protected]>

Author: c-wilson

src/structlog/threadlocal.py

@@ -216,6 +216,15 @@ def bind_threadlocal(**kwargs):
     _get_context().update(kwargs)
 
 
+def unbind_threadlocal(*keys):
+    """
+    Tries to remove bound *keys* from threadlocal logging context if present.
+    """
+    context = _get_context()
+    for key in keys:
+        context.pop(key, None)
+
+
 def _get_context():
     try:
         return _CONTEXT.context

tests/test_threadlocal.py

@@ -20,6 +20,7 @@
     merge_threadlocal,
     merge_threadlocal_context,
     tmp_bind,
+    unbind_threadlocal,
     wrap_dict,
 )
 
@@ -316,3 +317,21 @@ def test_multiple_binds(self):
         assert {"a": 1, "b": 2, "c": 3} == merge_threadlocal(
             None, None, {"b": 2}
         )
+
+    def test_unbind_threadlocal(self):
+        """
+        Test that unbinding from threadlocal works for keys that exist
+        and does not raise error when they do not exist.
+
+        """
+
+        clear_threadlocal()
+        bind_threadlocal(a=234, b=34)
+        assert {"a": 234, "b": 34} == merge_threadlocal_context(None, None, {})
+
+        unbind_threadlocal("a")
+
+        assert {"b": 34} == merge_threadlocal_context(None, None, {})
+
+        unbind_threadlocal("non-existing-key")
+        assert {"b": 34} == merge_threadlocal_context(None, None, {})