placeholder arg and pre-placeholder instance conversions to positional

dg-pb · Jun 25, 2024 · 266b4fa · 266b4fa
1 parent 1185510
commit 266b4fa
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Showing 3 changed files with 26 additions and 10 deletions.
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
@@ -366,8 +366,6 @@ The :mod:`functools` module defines the following functions:
 
       >>> from functools import partial, Placeholder
       >>> say_to_world = partial(print, Placeholder, Placeholder, "world!")
-      >>> say_to_world.placeholder_count
-      2
       >>> say_to_world('Hello', 'dear')
       Hello dear world!
 

diff --git a/Lib/inspect.py b/Lib/inspect.py
@@ -2052,9 +2052,13 @@ def _signature_get_partial(wrapped_sig, partial, extra_args=()):
                     new_params[param_name] = param.replace(default=arg_value)
                 else:
                     # was passed as a positional argument
-                    # But do not remove if it is a Placeholder
-                    if arg_value is not functools.Placeholder:
-                        new_params.pop(param.name)
+                    # Do not pop if it is a Placeholder
+                    #   and change kind to positional only
+                    if arg_value is functools.Placeholder:
+                        new_param = param.replace(kind=_POSITIONAL_ONLY)
+                        new_params[param_name] = new_param
+                    else:
+                        new_params.pop(param_name)
                     continue
 
             if param.kind is _KEYWORD_ONLY:
@@ -2548,6 +2552,11 @@ def _signature_from_callable(obj, *,
                 sig_params = tuple(sig.parameters.values())
                 assert (not sig_params or
                         first_wrapped_param is not sig_params[0])
+                # If there were placeholders set,
+                #   first param is transformaed to positional only
+                if partialmethod.args.count(functools.Placeholder):
+                    first_wrapped_param = first_wrapped_param.replace(
+                        kind=Parameter.POSITIONAL_ONLY)
                 new_params = (first_wrapped_param,) + sig_params
                 return sig.replace(parameters=new_params)
 

diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
@@ -3311,13 +3311,13 @@ def test(a, b, *, c, d):
 
         # With Placeholder
         self.assertEqual(self.signature(partial(test, Placeholder, 1)),
-                         ((('a', ..., ..., "positional_or_keyword"),
+                         ((('a', ..., ..., "positional_only"),
                            ('c', ..., ..., "keyword_only"),
                            ('d', ..., ..., "keyword_only")),
                           ...))
 
         self.assertEqual(self.signature(partial(test, Placeholder, 1, c=2)),
-                         ((('a', ..., ..., "positional_or_keyword"),
+                         ((('a', ..., ..., "positional_only"),
                            ('c', 2, ..., "keyword_only"),
                            ('d', ..., ..., "keyword_only")),
                           ...))
@@ -3369,6 +3369,15 @@ def test(a, *args, b, **kwargs):
                            ('kwargs', ..., ..., "var_keyword")),
                           ...))
 
+        # With Placeholder
+        p = partial(test, Placeholder, Placeholder, 1, b=0, test=1)
+        self.assertEqual(self.signature(p),
+                         ((('a', ..., ..., "positional_only"),
+                           ('args', ..., ..., "var_positional"),
+                           ('b', 0, ..., "keyword_only"),
+                           ('kwargs', ..., ..., "var_keyword")),
+                          ...))
+
         def test(a, b, c:int) -> 42:
             pass
 
@@ -3505,12 +3514,12 @@ def test(it, a, b, *, c) -> 'spam':
 
         # With Placeholder
         self.assertEqual(self.signature(Spam.bar, eval_str=False),
-                         ((('it', ..., ..., 'positional_or_keyword'),
-                           ('a', ..., ..., 'positional_or_keyword'),
+                         ((('it', ..., ..., 'positional_only'),
+                           ('a', ..., ..., 'positional_only'),
                            ('c', 1, ..., 'keyword_only')),
                           'spam'))
         self.assertEqual(self.signature(Spam().bar, eval_str=False),
-                         ((('a', ..., ..., 'positional_or_keyword'),
+                         ((('a', ..., ..., 'positional_only'),
                            ('c', 1, ..., 'keyword_only')),
                           'spam'))