wip version of __attrs_init_(). tests pass for py38

src/attr/_make.py

@@ -46,6 +46,10 @@
 # Unique object for unequivocal getattr() defaults.
 _sentinel = object()
 
+# Need a forward definition of Factory because _make_init() refers to
+# it, but since Factory is an attrs class, it calls _make_init()
+Factory = None
+
 
 class _Nothing(object):
     """
@@ -848,22 +852,38 @@ def add_hash(self):
 
         return self
 
-    def add_init(self):
-        self._cls_dict["__init__"] = self._add_method_dunders(
-            _make_init(
-                self._cls,
-                self._attrs,
-                self._has_post_init,
-                self._frozen,
-                self._slots,
-                self._cache_hash,
-                self._base_attr_map,
-                self._is_exc,
+    def add_init(self, init, auto_detect):
+        should_implement_init = _determine_whether_to_implement(
+            self._cls, init, auto_detect, ("__init__",)
+        )
+        attrs_init_method, init_method = _make_init(
+            self._cls,
+            self._attrs,
+            self._has_post_init,
+            self._frozen,
+            self._slots,
+            self._cache_hash,
+            self._base_attr_map,
+            self._is_exc,
+            (
                 self._on_setattr is not None
-                and self._on_setattr is not setters.NO_OP,
-            )
+                and self._on_setattr is not setters.NO_OP
+            ),
+            should_implement_init,
         )
 
+        self._cls_dict["__attrs_init__"] = self._add_method_dunders(
+            attrs_init_method
+        )
+        if init_method is not None:
+            self._cls_dict["__init__"] = self._add_method_dunders(init_method)
+        else:
+            if self._cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " init must be True."
+                )
+
         return self
 
     def add_eq(self):
@@ -1367,17 +1387,7 @@ def wrap(cls):
                 )
             builder.make_unhashable()
 
-        if _determine_whether_to_implement(
-            cls, init, auto_detect, ("__init__",)
-        ):
-            builder.add_init()
-        else:
-            if cache_hash:
-                raise TypeError(
-                    "Invalid value for cache_hash.  To use hash caching,"
-                    " init must be True."
-                )
-
+        builder.add_init(init, auto_detect)
         return builder.build_class()
 
     # maybe_cls's type depends on the usage of the decorator.  It's a class
@@ -1836,6 +1846,7 @@ def _make_init(
     base_attr_map,
     is_exc,
     has_global_on_setattr,
+    should_implement_init,
 ):
     if frozen and has_global_on_setattr:
         raise ValueError("Frozen classes can't use on_setattr.")
@@ -1872,6 +1883,7 @@ def _make_init(
         is_exc,
         needs_cached_setattr,
         has_global_on_setattr,
+        should_implement_init,
     )
     locs = {}
     bytecode = compile(script, unique_filename, "exec")
@@ -1893,10 +1905,16 @@ def _make_init(
         unique_filename,
     )
 
-    __init__ = locs["__init__"]
-    __init__.__annotations__ = annotations
+    __attrs_init__ = locs["__attrs_init__"]
+    __attrs_init__.__annotations__ = annotations
+
+    if "__init__" in locs:
+        __init__ = locs["__init__"]
+        __init__.__annotations__ = annotations
+    else:
+        __init__ = None
 
-    return __init__
+    return __attrs_init__, __init__
 
 
 def _setattr(attr_name, value_var, has_on_setattr):
@@ -2011,6 +2029,7 @@ def _attrs_to_init_script(
     is_exc,
     needs_cached_setattr,
     has_global_on_setattr,
+    should_implement_init,
 ):
     """
     Return a script of an initializer for *attrs* and a dict of globals.
@@ -2084,7 +2103,7 @@ def fmt_setter_with_converter(
         )
         arg_name = a.name.lstrip("_")
 
-        has_factory = isinstance(a.default, Factory)
+        has_factory = Factory is not None and isinstance(a.default, Factory)
         if has_factory and a.default.takes_self:
             maybe_self = "self"
         else:
@@ -2225,9 +2244,6 @@ def fmt_setter_with_converter(
             names_for_globals[val_name] = a.validator
             names_for_globals[attr_name] = a
 
-    if post_init:
-        lines.append("self.__attrs_post_init__()")
-
     # because this is set only after __attrs_post_init is called, a crash
     # will result if post-init tries to access the hash code.  This seemed
     # preferable to setting this beforehand, in which case alteration to
@@ -2263,12 +2279,30 @@ def fmt_setter_with_converter(
                 ", " if args else "",  # leading comma
                 ", ".join(kw_only_args),  # kw_only args
             )
+
+    init_lines = ""
+    if should_implement_init:
+        init_lines = """\
+
+def __init__(self, {args}):
+    args = locals()
+    del args['self']
+    self.__attrs_init__(**args)
+    {post_init_call}
+""".format(
+            args=args,
+            post_init_call="self.__attrs_post_init__()" if post_init else "",
+        )
+
     return (
         """\
-def __init__(self, {args}):
+def __attrs_init__(self, {args}):
     {lines}
+{init_lines}
 """.format(
-            args=args, lines="\n    ".join(lines) if lines else "pass"
+            args=args,
+            lines="\n    ".join(lines) if lines else "pass",
+            init_lines=init_lines,
         ),
         names_for_globals,
         annotations,

tests/test_dunders.py

@@ -59,7 +59,7 @@ def _add_init(cls, frozen):
     This function used to be part of _make.  It wasn't used anymore however
     the tests for it are still useful to test the behavior of _make_init.
     """
-    cls.__init__ = _make_init(
+    cls.__attrs_init__, cls.__init__ = _make_init(
         cls,
         cls.__attrs_attrs__,
         getattr(cls, "__attrs_post_init__", False),
@@ -69,6 +69,7 @@ def _add_init(cls, frozen):
         base_attr_map={},
         is_exc=False,
         has_global_on_setattr=False,
+        should_implement_init=True,
     )
     return cls
 

tests/test_make.py

@@ -1526,7 +1526,7 @@ class C(object):
             b.add_eq()
             .add_order()
             .add_hash()
-            .add_init()
+            .add_init(True, True)
             .add_repr("ns")
             .add_str()
             .build_class()