Improve partial method system beeware#148 beeware#453

src/rubicon/objc/api.py

@@ -246,28 +246,30 @@ def __repr__(self):
         return f"{type(self).__qualname__}({self.name_start!r})"
 
     def __call__(self, receiver, first_arg=_sentinel, **kwargs):
-        if first_arg is ObjCPartialMethod._sentinel:
+        # Ignore parts of argument names after "__".
+        order = [argname.split("__")[0] for argname in kwargs]
+        args = [arg for arg in kwargs.values()]
+
+        if first_arg is self._sentinel:
             if kwargs:
+                # This will be deleted when #26 is introduced.
                 raise TypeError("Missing first (positional) argument")
-
-            args = []
-            rest = frozenset()
+            rest = (*order,)
         else:
-            args = [first_arg]
-            # Add "" to rest to indicate that the method takes arguments
-            rest = frozenset(kwargs) | frozenset(("",))
+            args.insert(0, first_arg)
+            rest = ("", *order)
 
         try:
-            name, order = self.methods[rest]
+            name = self.methods[rest]
         except KeyError:
             raise ValueError(
-                f"No method was found starting with {self.name_start!r} and with keywords {set(kwargs)}\n"
+                f"No method was found starting with {self.name_start!r} and with keywords {(*kwargs,)}\n"
                 f"Known keywords are:\n"
                 + "\n".join(repr(keywords) for keywords in self.methods)
             )
 
         meth = receiver.objc_class._cache_method(name)
-        args += [kwargs[name] for name in order]
+
         return meth(receiver, *args)
 
 
@@ -1035,28 +1037,11 @@ def __getattr__(self, name):
 
         The "interleaved" syntax is usually preferred, since it looks more
         similar to normal Objective-C syntax. However, the "flat" syntax is also
-        fully supported. Certain method names require the "flat" syntax, for
-        example if two arguments have the same label (e.g.
-        ``performSelector:withObject:withObject:``), which is not supported by
-        Python's keyword argument syntax.
-
-        .. warning::
-
-            The "interleaved" syntax currently ignores the ordering of its
-            keyword arguments. However, in the interest of readability, the
-            keyword arguments should always be passed in the same order as they
-            appear in the method name.
-
-            This also means that two methods whose names which differ only in
-            the ordering of their keywords will conflict with each other, and
-            can only be called reliably using "flat" syntax.
-
-            As of Python 3.6, the order of keyword arguments passed to functions
-            is preserved (:pep:`468`). In the future, once Rubicon requires
-            Python 3.6 or newer, "interleaved" method calls will respect keyword
-            argument order. This will fix the kind of conflict described above,
-            but will also disallow specifying the keyword arguments out of
-            order.
+        fully supported. If two arguments have the same label (e.g.
+        ``performSelector:withObject:withObject:``), you can use ``__`` in the
+        keywords like ``performSelector(..., withObject__1=...,
+        withObject__2=...)``. The parts after ``__`` can be anything you can use
+        as argument names.
         """
         # Search for named instance method in the class object and if it
         # exists, return callable object with self as hidden argument.
@@ -1090,7 +1075,7 @@ def __getattr__(self, name):
         else:
             method = None
 
-        if method is None or set(method.methods) == {frozenset()}:
+        if method is None or set(method.methods) == {()}:
             # Find a method whose full name matches the given name if no partial
             # method was found, or the partial method can only resolve to a
             # single method that takes no arguments. The latter case avoids
@@ -1654,20 +1639,23 @@ def _load_methods(self):
             name = libobjc.method_getName(method).name.decode("utf-8")
             self.instance_method_ptrs[name] = method
 
-            first, *rest = name.split(":")
-            # Selectors end in a colon iff the method takes arguments.
-            # Because of this, rest must either be empty (method takes no arguments)
-            # or the last element must be an empty string (method takes arguments).
-            assert not rest or rest[-1] == ""
+            # Selectors end with a colon if the method takes arguments.
+            if name.endswith(":"):
+                first, *rest, _ = name.split(":")
+                # Insert an empty string in order to indicate that the method
+                # takes a first argument as a positional argument.
+                rest.insert(0, "")
+                rest = tuple(rest)
+            else:
+                first = name
+                rest = ()
 
             try:
                 partial = self.partial_methods[first]
             except KeyError:
                 partial = self.partial_methods[first] = ObjCPartialMethod(first)
 
-            # order is rest without the dummy "" part
-            order = rest[:-1]
-            partial.methods[frozenset(rest)] = (name, order)
+            partial.methods[rest] = name
 
         # Set the list of methods for the class to the computed list.
         self.methods_ptr = methods_ptr

tests/objc/Example.h

@@ -103,6 +103,10 @@ extern NSString *const SomeGlobalStringConstant;
 +(NSUInteger) overloaded;
 +(NSUInteger) overloaded:(NSUInteger)arg1;
 +(NSUInteger) overloaded:(NSUInteger)arg1 extraArg:(NSUInteger)arg2;
++(NSUInteger) overloaded:(NSUInteger)arg extraArg1:(NSUInteger)arg1 extraArg2:(NSUInteger)arg2;
++(NSUInteger) overloaded:(NSUInteger)arg extraArg2:(NSUInteger)arg2 extraArg1:(NSUInteger)arg1;
++(NSUInteger) overloaded:(NSUInteger)arg orderedArg1:(NSUInteger)arg1 orderedArg2:(NSUInteger)arg2;
++(NSUInteger) overloaded:(NSUInteger)arg duplicateArg:(NSUInteger)arg1 duplicateArg:(NSUInteger)arg2;
 
 +(struct complex) doStuffWithStruct:(struct simple)simple;
 

tests/objc/Example.m

@@ -241,6 +241,26 @@ +(NSUInteger) overloaded:(NSUInteger)arg1 extraArg:(NSUInteger)arg2
     return arg1 + arg2;
 }
 
++(NSUInteger) overloaded:(NSUInteger)arg extraArg1:(NSUInteger)arg1 extraArg2:(NSUInteger)arg2
+{
+    return 1;
+}
+
++(NSUInteger) overloaded:(NSUInteger)arg extraArg2:(NSUInteger)arg2 extraArg1:(NSUInteger)arg1
+{
+    return 2;
+}
+
++(NSUInteger) overloaded:(NSUInteger)arg orderedArg1:(NSUInteger)arg1 orderedArg2:(NSUInteger)arg2
+{
+    return 0;
+}
+
++(NSUInteger) overloaded:(NSUInteger)arg duplicateArg:(NSUInteger)arg1 duplicateArg:(NSUInteger)arg2
+{
+    return arg1 + arg2;
+}
+
 +(struct complex) doStuffWithStruct:(struct simple)simple
 {
     return (struct complex){

tests/test_core.py

@@ -986,6 +986,22 @@ def test_partial_method_lots_of_args(self):
         )
         self.assertEqual(buf.value.decode("utf-8"), pystring)
 
+    def test_partial_method_arg_order(self):
+        Example = ObjCClass("Example")
+
+        self.assertEqual(Example.overloaded(0, extraArg1=0, extraArg2=0), 1)
+        self.assertEqual(Example.overloaded(0, extraArg2=0, extraArg1=0), 2)
+
+        with self.assertRaises(ValueError):
+            Example.overloaded(0, orderedArg2=0, orderedArg1=0)
+
+    def test_partial_method_duplicate_arg_names(self):
+        Example = ObjCClass("Example")
+        self.assertEqual(
+            Example.overloaded(0, duplicateArg__a=14, duplicateArg__b=24),
+            14 + 24,
+        )
+
     def test_objcmethod_str_repr(self):
         """Test ObjCMethod, ObjCPartialMethod, and ObjCBoundMethod str and repr"""