Deprecated decorator: add support for class methods. (#27)

Author: jayaddison

pywisetransfer/deprecation.py

@@ -11,22 +11,44 @@ class deprecated:
     https://blog.miguelgrinberg.com/post/the-ultimate-guide-to-python-decorators-part-iii-decorators-with-arguments
     """
 
+    @staticmethod
+    def _message(message=None, *args, **kwargs):
+        return message
+
     def __init__(self, *args, **kwargs):
+        self.f = None
         if len(args) == 1 and callable(args[0]):
-            self.f = args[0]
-            message = args[1] if len(args) > 1 else None
-        else:
-            self.f = None
-            message = args[0] if len(args) == 1 else None
-        self.message = kwargs.get("message", message)
+            global f
+            f = orig = args[0]
+            exec(
+                f"""
+class deprecated(deprecated):
+    @staticmethod
+    def {f.__name__}(*args, **kwargs):
+        self._emit_warning()
+        return orig(*args, **kwargs)
+
+f = deprecated.{f.__name__}
+""",
+                locals(),
+                globals(),
+            )
+            self.f = f
+            args = args[1:]
+        self.message = self._message(*args, **kwargs)
+
+    def _emit_warning(self):
+        warnings.warn(self.message, DeprecationWarning, stacklevel=3)
 
     def __call__(self, *args, **kwargs):
-        if self.f is None and len(args) == 1 and callable(args[0]):
-            self.f = args[0]
-            return self
-
-        warnings.warn(self.message, DeprecationWarning, stacklevel=2)
-        return self.f(*args, **kwargs)
+        if self.f:
+            return self.f(*args, **kwargs)
+        else:
+            assert len(args) == 1 and callable(args[0])
+            return deprecated(args[0], message=self.message).f
 
     def __repr__(self):
-        return f"<deprecated {repr(self.f)}>"
+        if self.f:
+            return repr(self.f)
+        else:
+            return f"<deprecation decorator ({self.message!r})>"

test/test_deprecation.py

@@ -4,56 +4,72 @@
 
 from pywisetransfer.deprecation import deprecated
 
-record_warnings = lambda: catch_warnings(record=True)
 
+def record_warnings():
+    return catch_warnings(record=True)
 
-def undecorated():
-    return 1
+
+def undecorated(n):
+    return n
 
 
 @deprecated
-def bare_decorator():
-    return 1
+def bare_decorator(n):
+    return n + 1
 
 
 @deprecated()
-def zero_args_decorator():
-    return 1
+def zero_args_decorator(n):
+    return n + 2
 
 
 @deprecated("positional")
-def posarg_decorator():
-    return 1
+def posarg_decorator(n):
+    return n + 3
 
 
 @deprecated(message="keyword")
-def kwarg_decorator():
-    return 1
+def kwarg_decorator(n):
+    return n + 4
+
+
+class Class:
+    base = 2
+
+    @deprecated(message="method")
+    def method_decorator(self, n):
+        return self.base + n + 3
 
 
 @pytest.mark.parametrize(
-    "func, name, deprecated, message",
+    "func, name, deprecated, result, message",
     [
-        (undecorated, "undecorated", False, None),
-        (bare_decorator, "bare_decorator", True, None),
-        (zero_args_decorator, "zero_args_decorator", True, None),
-        (posarg_decorator, "posarg_decorator", True, "positional"),
-        (kwarg_decorator, "kwarg_decorator", True, "keyword"),
+        (undecorated, "undecorated", False, 0, None),
+        (bare_decorator, "bare_decorator", True, 1, None),
+        (zero_args_decorator, "zero_args_decorator", True, 2, None),
+        (posarg_decorator, "posarg_decorator", True, 3, "positional"),
+        (kwarg_decorator, "kwarg_decorator", True, 4, "keyword"),
+        (Class().method_decorator, "method_decorator", True, 5, "method"),
     ],
 )
-def test_no_decorator(func, name, deprecated, message):
+def test_decorator_variants(func, name, deprecated, result, message):
     actual_repr = repr(func)
     with record_warnings() as ws:
-        result = func()
+        actual_result = func(0)
 
     # Check the Python repr of the function
     assert name in actual_repr
-    actual_deprecated = "deprecated" in actual_repr
+    actual_deprecated = "deprecated." in actual_repr
     assert deprecated == actual_deprecated
 
     # Check the behaviour of the function
-    assert result == 1
+    assert result == actual_result
 
     # Check the warnings emitted by the function
-    assert ws if deprecated else not ws
+    assert len(ws) == 1 if deprecated else not ws
     assert any([message in str(w.message) for w in ws] if message else [True])
+
+
+def test_standalone_decorator_repr():
+    decorator = deprecated(message="standalone")
+    assert repr(decorator) == "<deprecation decorator ('standalone')>"