Merge pull request #267 from ahrefs/mj-dedup-decorator

atdpy fix: Avoid applying the `@dataclass` decorator twice

CHANGES.md

@@ -1,3 +1,10 @@
+Next
+-----------------
+
+* atdpy: don't apply the `@dataclass` decorator twice if explicitly
+  added by the user via an ATD annotation such as
+  `<python decorator="dataclass(frozen=True)">` (#267)
+
 2.4.0 (2022-03-24)
 -----------------
 

atdpy.opam

@@ -66,6 +66,7 @@ depends: [
   "atd" {>= "2.3.0"}
   "atdgen" {>= "2.3.0"}
   "cmdliner" {>= "1.1.0"}
+  "re"
   "alcotest" {with-test}
   "conf-python-3" {with-test}
   "odoc" {with-doc}

atdpy/src/lib/Codegen.ml

@@ -847,7 +847,6 @@ let record env ~class_decorators loc name (fields : field list) an =
   in
   [
     Inline class_decorators;
-    Line "@dataclass";
     Line (sprintf "class %s:" py_class_name);
     Block (spaced [
       Line (sprintf {|"""Original type: %s = { ... }"""|} name);
@@ -880,7 +879,6 @@ let alias_wrapper env ~class_decorators name type_expr =
   let value_type = type_name_of_expr env type_expr in
   [
     Inline class_decorators;
-    Line "@dataclass";
     Line (sprintf "class %s:" py_class_name);
     Block [
       Line (sprintf {|"""Original type: %s"""|} name);
@@ -1058,7 +1056,6 @@ let sum_container env ~class_decorators loc name cases =
   in
   [
     Inline class_decorators;
-    Line "@dataclass";
     Line (sprintf "class %s:" py_class_name);
     Block [
       Line (sprintf {|"""Original type: %s = [ ... ]"""|} name);
@@ -1122,11 +1119,24 @@ let sum env ~class_decorators loc name cases =
   ]
   |> double_spaced
 
+let uses_dataclass_decorator =
+  let rex = Re.Pcre.regexp {|\A[ \t\r\n]*dataclass(\(|[ \t\r\n]|\z)|} in
+  fun s -> Re.Pcre.pmatch ~rex s
+
+let get_class_decorators an =
+  let decorators = Python_annot.get_python_decorators an in
+  (* Avoid duplicate use of the @dataclass decorator, which doesn't work
+     if some options like frozen=True are used. *)
+  if List.exists uses_dataclass_decorator decorators then
+    decorators
+  else
+    decorators @ ["dataclass"]
+
 let type_def env ((loc, (name, param, an), e) : A.type_def) : B.t =
   if param <> [] then
     not_implemented loc "parametrized type";
   let class_decorators =
-    Python_annot.get_python_decorators an
+    get_class_decorators an
     |> List.map (fun s -> Line ("@" ^ s))
   in
   let rec unwrap e =

atdpy/src/lib/dune

@@ -1,6 +1,7 @@
 (library
  (name atdpy)
  (libraries
+   re
    atd
    atdgen_emit
  )

atdpy/test/python-expected/everything.py

@@ -441,7 +441,6 @@ def to_json_string(self, **kw: Any) -> str:
 @deco.deco1
 @deco.deco2(42)
 @dataclass(order=True)
-@dataclass
 class RequireField:
     """Original type: require_field = { ... }"""
 

dune-project

@@ -166,6 +166,7 @@ automatically handled")
   (atd (>= 2.3.0))
   (atdgen (>= 2.3.0))
   (cmdliner (>= 1.1.0))
+  re
   (alcotest :with-test)
   (conf-python-3 :with-test)
   (odoc :with-doc)))