Start using inspect.signature for CompiledObject params.

Fixes 917 and 924.

jedi/evaluate/compiled/__init__.py

@@ -115,6 +115,9 @@ class CompiledObject(Context):
         return inspect.getdoc(self.obj) or ''
 
     def get_param_names(self):
+        try:
+            signature = inspect.signature(self.obj)
+        except ValueError:  # Has no signature
             params_str, ret = self._parse_function_doc()
             tokens = params_str.split(',')
             if inspect.ismethoddescriptor(self.obj):
@@ -122,6 +125,9 @@ class CompiledObject(Context):
             for p in tokens:
                 parts = p.strip().split('=')
                 yield UnresolvableParamName(self, parts[0])
+        else:
+            for signature_param in signature.parameters.values():
+                yield SignatureParamName(self, signature_param)
 
     def __repr__(self):
         return '<%s: %s>' % (self.__class__.__name__, repr(self.obj))
@@ -276,6 +282,29 @@ class CompiledName(AbstractNameDefinition):
         return [_create_from_name(self._evaluator, module, self.parent_context, self.string_name)]
 
 
+class SignatureParamName(AbstractNameDefinition):
+    api_type = 'param'
+
+    def __init__(self, compiled_obj, signature_param):
+        self.parent_context = compiled_obj.parent_context
+        self._signature_param = signature_param
+
+    @property
+    def string_name(self):
+        return self._signature_param.name
+
+    def infer(self):
+        p = self._signature_param
+        evaluator = self.parent_context.evaluator
+        types = set()
+        if p.default is not p.empty:
+            types.add(create(evaluator, p.default))
+        if p.annotation is not p.empty:
+            annotation = create(evaluator, p.annotation)
+            types |= annotation.execute_evaluated()
+        return types
+
+
 class UnresolvableParamName(AbstractNameDefinition):
     api_type = 'param'
 

test/test_api/test_interpreter.py

@@ -1,9 +1,10 @@
 """
 Tests of ``jedi.api.Interpreter``.
 """
+import pytest
 
 import jedi
-from jedi._compatibility import is_py33
+from jedi._compatibility import is_py33, exec_function, py_version
 from jedi.evaluate.compiled import mixed
 
 
@@ -225,3 +226,29 @@ def test_endless_yield():
     # If iterating over lists it should not be possible to take an extremely
     # long time.
     _assert_interpreter_complete('list(lst)[9000].rea', locals(), ['real'])
+
+
+@pytest.mark.skipif('py_version < 33', reason='inspect.signature was created in 3.3.')
+def test_completion_params():
+    foo = lambda a, b=3: None
+
+    script = jedi.Interpreter('foo', [locals()])
+    c, = script.completions()
+    assert [p.name for p in c.params] == ['a', 'b']
+    assert c.params[0]._goto_definitions() == []
+    t, = c.params[1]._goto_definitions()
+    assert t.name == 'int'
+
+
+@pytest.mark.skipif('py_version < 33', reason='inspect.signature was created in 3.3.')
+def test_completion_param_annotations():
+    # Need to define this function not directly in Python. Otherwise Jedi is to
+    # clever and uses the Python code instead of the signature object.
+    code = 'def foo(a: 1, b: str, c: int = 1.0): pass'
+    exec_function(code, locals())
+    script = jedi.Interpreter('foo', [locals()])
+    c, = script.completions()
+    a, b, c = c.params
+    assert a._goto_definitions() == []
+    assert [d.name for d in b._goto_definitions()] == ['str']
+    assert [d.name for d in c._goto_definitions()] == ['int', 'float']