Support initializing structs via keyword arguments

mrbgems/mruby-struct/src/struct.c

@@ -317,6 +317,46 @@ mrb_struct_initialize_withArg(mrb_state *mrb, mrb_int argc, const mrb_value *arg
   return self;
 }
 
+static mrb_value
+mrb_struct_initialize_withKw(mrb_state *mrb, mrb_value hash, mrb_value self)
+{
+  mrb_value members = struct_members(mrb, self);
+  mrb_int member_count = num_members(mrb, self);
+
+  /* Initialize members from hash, defaulting to nil */
+  for (mrb_int i = 0; i < member_count; i++) {
+    mrb_value member = RARRAY_PTR(members)[i];
+    if (mrb_hash_key_p(mrb, hash, member)) {
+      mrb_value val = mrb_hash_get(mrb, hash, member);
+      mrb_ary_set(mrb, self, i, val);
+    }
+    else {
+      mrb_ary_set(mrb, self, i, mrb_nil_value());
+    }
+  }
+
+  /* Check if all keys in the hash are valid members */
+  mrb_value keys = mrb_hash_keys(mrb, hash);
+  mrb_value invalid_keys = mrb_ary_new(mrb);
+
+  for (mrb_int i = 0; i < RARRAY_LEN(keys); i++) {
+    mrb_value key = RARRAY_PTR(keys)[i];
+    mrb_value include_result = mrb_funcall(mrb, members, "include?", 1, key);
+    if (mrb_test(include_result) == FALSE) {
+      mrb_ary_push(mrb, invalid_keys, key);
+    }
+  }
+
+  /* If there are any invalid keys, raise an error with all of them */
+  if (RARRAY_LEN(invalid_keys) > 0) {
+    mrb_value keys_str = mrb_funcall(mrb, invalid_keys, "join", 1, mrb_str_new_lit(mrb, ", "));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unknown keyword%s: %S",
+              RARRAY_LEN(invalid_keys) > 1 ? "s" : "", keys_str);
+  }
+
+  return self;
+}
+
 static mrb_value
 mrb_struct_initialize(mrb_state *mrb, mrb_value self)
 {
@@ -324,7 +364,13 @@ mrb_struct_initialize(mrb_state *mrb, mrb_value self)
   mrb_int argc;
 
   mrb_get_args(mrb, "*", &argv, &argc);
-  return mrb_struct_initialize_withArg(mrb, argc, argv, self);
+
+  /* If we get a single hash argument, treat it as keyword arguments */
+  if (argc == 1 && mrb_hash_p(argv[0])) {
+    return mrb_struct_initialize_withKw(mrb, argv[0], self);
+  } else {
+    return mrb_struct_initialize_withArg(mrb, argc, argv, self);
+  }
 }
 
 /* 15.2.18.4.9  */

mrbgems/mruby-struct/test/struct.rb

@@ -229,3 +229,23 @@ assert 'method visibility with Struct' do
     c.new.bad!
   end
 end
+
+assert "Struct initialize with keyword arguments" do
+  c = Struct.new(:foo, :bar)
+
+  o = c.new(foo: 1, bar: 2)
+  assert_equal 1, o.foo
+  assert_equal 2, o.bar
+
+  o2 = c.new(bar: 1, foo: 2)
+  assert_equal 2, o2.foo
+  assert_equal 1, o2.bar
+
+  o3 = c.new(foo: :test)
+  assert_equal :test, o3.foo
+  assert_equal nil, o3.bar
+
+  assert_raise_with_message_pattern(ArgumentError, "unknown keywords: roo, baq") do
+    c.new(foo: 1, roo: nil, baq: :test)
+  end
+end