bpo-19903: Change to inspect.signature for calltips

This commit change the get_argspec from using inspect.getfullargspec
to inspect.signature. It will improve the tip message for use.

Also, if object is not callable, now will return this message for
user, not blank tips. If the methods has an invalid method signature,
it will also return message to user.

Author: mlouielu

Lib/idlelib/calltips.py

@@ -122,6 +122,8 @@ def get_entity(expression):
 _INDENT = ' '*4  # for wrapped signatures
 _first_param = re.compile(r'(?<=\()\w*\,?\s*')
 _default_callable_argspec = "See source or doc"
+_invalid_method = "invalid method signature"
+_argument_positional = "('/' marks preceding arguments as positional-only)"
 
 
 def get_argspec(ob):
@@ -138,17 +140,31 @@ def get_argspec(ob):
         ob_call = ob.__call__
     except BaseException:
         return argspec
-    if isinstance(ob, type):
-        fob = ob.__init__
-    elif isinstance(ob_call, types.MethodType):
+    if isinstance(ob_call, types.MethodType):
         fob = ob_call
     else:
         fob = ob
-    if isinstance(fob, (types.FunctionType, types.MethodType)):
-        argspec = inspect.formatargspec(*inspect.getfullargspec(fob))
-        if (isinstance(ob, (type, types.MethodType)) or
-                isinstance(ob_call, types.MethodType)):
-            argspec = _first_param.sub("", argspec)
+
+    try:
+        argspec = str(inspect.signature(fob))
+    except ValueError as err:
+        msg = str(err)
+        if msg.startswith(_invalid_method):
+            argspec = _invalid_method
+            return argspec
+        elif msg.startswith('no signature found for'):
+            """If no signature found for function or method"""
+            pass
+        else:
+            """Callable is not supported by signature"""
+            pass
+
+    if '/' in argspec:
+        """Using AC's positional argument should add the explain"""
+        argspec = '\n'.join([argspec, _argument_positional])
+    if isinstance(fob, type) and argspec == '()':
+        """fob with no argument, use default callable argspec"""
+        argspec = _default_callable_argspec
 
     lines = (textwrap.wrap(argspec, _MAX_COLS, subsequent_indent=_INDENT)
             if len(argspec) > _MAX_COLS else [argspec] if argspec else [])

Lib/idlelib/idle_test/test_calltips.py

@@ -46,25 +46,36 @@ def test_builtins(self):
 
         # Python class that inherits builtin methods
         class List(list): "List() doc"
+
         # Simulate builtin with no docstring for default tip test
         class SB:  __call__ = None
 
         def gtest(obj, out):
             self.assertEqual(signature(obj), out)
 
         if List.__doc__ is not None:
-            gtest(List, List.__doc__)
+            gtest(List, '(iterable=(), /)\n' + ct._argument_positional + '\n' +
+                  List.__doc__)
         gtest(list.__new__,
-               'Create and return a new object.  See help(type) for accurate signature.')
+               '(*args, **kwargs)\nCreate and return a new object.  See help(type) for accurate signature.')
         gtest(list.__init__,
+               '(self, /, *args, **kwargs)\n' + ct._argument_positional + '\n' +
                'Initialize self.  See help(type(self)) for accurate signature.')
-        append_doc =  "Append object to the end of the list."
-        gtest(list.append, append_doc)
-        gtest([].append, append_doc)
-        gtest(List.append, append_doc)
+        append_doc = ct._argument_positional + '\n' + "Append object to the end of the list."
+        gtest(list.append, '(self, object, /)\n' + append_doc)
+        gtest(List.append, '(self, object, /)\n' + append_doc)
+        gtest([].append, '(object, /)\n' + append_doc)
 
         gtest(types.MethodType, "method(function, instance)")
         gtest(SB(), default_tip)
+        import re
+        p = re.compile('')
+        gtest(re.sub, '''(pattern, repl, string, count=0, flags=0)\nReturn the string obtained by replacing the leftmost
+non-overlapping occurrences of the pattern in string by the
+replacement repl.  repl can be either a string or a callable;
+if a string, backslash escapes in it are processed.  If it is
+a callable, it's passed the match object and must return''')
+        gtest(p.sub, '''(repl, string, count=0)\nReturn the string obtained by replacing the leftmost non-overlapping occurrences o...''')
 
     def test_signature_wrap(self):
         if textwrap.TextWrapper.__doc__ is not None:
@@ -132,12 +143,20 @@ def test_starred_parameter(self):
         # test that starred first parameter is *not* removed from argspec
         class C:
             def m1(*args): pass
-            def m2(**kwds): pass
         c = C()
-        for meth, mtip  in ((C.m1, '(*args)'), (c.m1, "(*args)"),
-                                      (C.m2, "(**kwds)"), (c.m2, "(**kwds)"),):
+        for meth, mtip  in ((C.m1, '(*args)'), (c.m1, "(*args)"),):
             self.assertEqual(signature(meth), mtip)
 
+    def test_invalid_method_signature(self):
+        class C:
+            def m2(**kwargs): pass
+        class Test:
+            def __call__(*, a): pass
+
+        mtip = ct._invalid_method
+        self.assertEqual(signature(C().m2), mtip)
+        self.assertEqual(signature(Test()), mtip)
+
     def test_non_ascii_name(self):
         # test that re works to delete a first parameter name that
         # includes non-ascii chars, such as various forms of A.
@@ -156,17 +175,23 @@ def test_attribute_exception(self):
         class NoCall:
             def __getattr__(self, name):
                 raise BaseException
-        class Call(NoCall):
+        class CallA(NoCall):
+            def __call__(oui, a, b, c):
+                pass
+        class CallB(NoCall):
             def __call__(self, ci):
                 pass
-        for meth, mtip  in ((NoCall, default_tip), (Call, default_tip),
-                            (NoCall(), ''), (Call(), '(ci)')):
+
+        for meth, mtip  in ((NoCall, default_tip), (CallA, default_tip),
+                            (NoCall(), ''), (CallA(), '(a, b, c)'),
+                            (CallB(), '(ci)')):
             self.assertEqual(signature(meth), mtip)
 
     def test_non_callables(self):
         for obj in (0, 0.0, '0', b'0', [], {}):
             self.assertEqual(signature(obj), '')
 
+
 class Get_entityTest(unittest.TestCase):
     def test_bad_entity(self):
         self.assertIsNone(ct.get_entity('1/0'))