Dataclass progress

conftest.py

@@ -140,3 +140,11 @@ def skip_pre_python38(environment):
         # This if is just needed to avoid that tests ever skip way more than
         # they should for all Python versions.
         pytest.skip()
+
+
+@pytest.fixture()
+def skip_pre_python37(environment):
+    if environment.version_info < (3, 7):
+        # This if is just needed to avoid that tests ever skip way more than
+        # they should for all Python versions.
+        pytest.skip()

jedi/evaluate/context/klass.py

@@ -198,12 +198,7 @@ class ClassMixin(object):
                 yield f
 
         if search_global:
-            yield ParserTreeFilter(
-                self.evaluator,
-                context=self,
-                until_position=until_position,
-                origin_scope=origin_scope
-            )
+            yield self.get_global_filter(until_position, origin_scope)
         else:
             for cls in self.py__mro__():
                 if isinstance(cls, compiled.CompiledObject):
@@ -227,6 +222,14 @@ class ClassMixin(object):
                     next(instance_filters)
                     yield next(instance_filters)
 
+    def get_global_filter(self, until_position=None, origin_scope=None):
+        return ParserTreeFilter(
+            self.evaluator,
+            context=self,
+            until_position=until_position,
+            origin_scope=origin_scope
+        )
+
 
 class ClassContext(use_metaclass(CachedMetaClass, ClassMixin, FunctionAndClassBase)):
     """

jedi/plugins/stdlib.py

@@ -520,6 +520,37 @@ def _random_choice(sequences):
     )
 
 
+def _dataclass(obj, arguments):
+    for c in _follow_param(obj.evaluator, arguments, 0):
+        if c.is_class():
+            return ContextSet([DataclassWrapper(c)])
+        else:
+            return ContextSet([obj])
+    return NO_CONTEXTS
+
+
+class DataclassWrapper(ContextWrapper):
+    def get_signatures(self):
+        params = []
+        for cls in reversed(self._wrapped_context.py__mro__()):
+            if isinstance(cls, ClassContext) and not cls.is_stub():
+                filter_ = cls.get_global_filter()
+                print(filter_)
+                for name in filter_.values():
+                    d = name.tree_name.get_definition()
+                    if d.type == 'expr_stmt' and d.children[1].type == 'annassign':
+                        params.append()
+        return [DataclassSignature(cls, params)]
+
+
+class DataclassSignature(AbstractSignature):
+    def __init__(self, context, params):
+        super(DataclassSignature, self).__init__(context)
+        self._params = params
+
+    def get_param_names(self):
+
+
 class ItemGetterCallable(ContextWrapper):
     def __init__(self, instance, args_context_set):
         super(ItemGetterCallable, self).__init__(instance)
@@ -602,7 +633,7 @@ _implemented = {
     },
     'dataclasses': {
         # For now this works at least better than Jedi trying to understand it.
-        'dataclass': lambda obj, arguments: NO_CONTEXTS,
+        'dataclass': _dataclass
     },
 }
 

test/test_evaluate/test_signature.py

@@ -1,6 +1,8 @@
-import pytest
+from textwrap import dedent
 from operator import ge, lt
 
+import pytest
+
 from jedi.evaluate.gradual.conversion import _stub_to_python_context_set
 
 
@@ -60,3 +62,20 @@ def test_pow_signature(Script):
                        'pow(x: float, y: float, /) -> float',
                        'pow(x: int, y: int, z: int, /) -> Any',
                        'pow(x: int, y: int, /) -> Any'}
+
+
+@pytest.mark.parametrize('decorator', ['@dataclass', '@dataclass(eq=True)'])
+def test_dataclass_signature(Script, skip_pre_python37, decorator):
+    code = dedent('''
+        class InventoryItem:
+            name: str
+            foo = 3
+            unit_price: float
+            quantity_on_hand: int = 0
+
+        InventoryItem(''')
+
+    code = 'from dataclasses import dataclass\n' + decorator + code
+
+    sig, = Script(code).call_signatures()
+    assert [p.name for p in sig.params] == ['name', 'unit_price', 'quantity_on_hand']