attr_reader, attr_writer, attr_accessor and attr methods returns array of symbols (#3935)

Co-authored-by: Yusuke Endoh <mame@ruby-lang.org>

object.c

@@ -2264,17 +2264,21 @@ id_for_attr(VALUE obj, VALUE name)
  *  value of each instance variable. Equivalent to calling
  *  ``<code>attr</code><i>:name</i>'' on each name in turn.
  *  String arguments are converted to symbols.
+ *  Returns an array of defined methods names as symbols.
  */
 
 static VALUE
 rb_mod_attr_reader(int argc, VALUE *argv, VALUE klass)
 {
     int i;
+    VALUE names = rb_ary_new2(argc);
 
     for (i=0; i<argc; i++) {
-	rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, FALSE, TRUE);
+	ID id = id_for_attr(klass, argv[i]);
+	rb_attr(klass, id, TRUE, FALSE, TRUE);
+	rb_ary_push(names, ID2SYM(id));
     }
-    return Qnil;
+    return names;
 }
 
 /**
@@ -2286,6 +2290,7 @@ rb_mod_attr_reader(int argc, VALUE *argv, VALUE klass)
  *  The first form is equivalent to #attr_reader.
  *  The second form is equivalent to <code>attr_accessor(name)</code> but deprecated.
  *  The last form is equivalent to <code>attr_reader(name)</code> but deprecated.
+ *  Returns an array of defined methods names as symbols.
  *--
  * \private
  * \todo can be static?
@@ -2295,9 +2300,14 @@ VALUE
 rb_mod_attr(int argc, VALUE *argv, VALUE klass)
 {
     if (argc == 2 && (argv[1] == Qtrue || argv[1] == Qfalse)) {
-        rb_category_warning(RB_WARN_CATEGORY_DEPRECATED, "optional boolean argument is obsoleted");
-	rb_attr(klass, id_for_attr(klass, argv[0]), 1, RTEST(argv[1]), TRUE);
-	return Qnil;
+	ID id = id_for_attr(klass, argv[0]);
+	VALUE names = rb_ary_new();
+
+	rb_category_warning(RB_WARN_CATEGORY_DEPRECATED, "optional boolean argument is obsoleted");
+	rb_attr(klass, id, 1, RTEST(argv[1]), TRUE);
+	rb_ary_push(names, ID2SYM(id));
+	if (argv[1] == Qtrue) rb_ary_push(names, rb_str_intern(rb_sprintf("%"PRIsVALUE"=", ID2SYM(id))));
+	return names;
     }
     return rb_mod_attr_reader(argc, argv, klass);
 }
@@ -2310,17 +2320,21 @@ rb_mod_attr(int argc, VALUE *argv, VALUE klass)
  *  Creates an accessor method to allow assignment to the attribute
  *  <i>symbol</i><code>.id2name</code>.
  *  String arguments are converted to symbols.
+ *  Returns an array of defined methods names as symbols.
  */
 
 static VALUE
 rb_mod_attr_writer(int argc, VALUE *argv, VALUE klass)
 {
     int i;
+    VALUE names = rb_ary_new2(argc);
 
     for (i=0; i<argc; i++) {
-	rb_attr(klass, id_for_attr(klass, argv[i]), FALSE, TRUE, TRUE);
+	ID id = id_for_attr(klass, argv[i]);
+	rb_attr(klass, id, FALSE, TRUE, TRUE);
+	rb_ary_push(names, rb_str_intern(rb_sprintf("%"PRIsVALUE"=", ID2SYM(id))));
     }
-    return Qnil;
+    return names;
 }
 
 /*
@@ -2333,6 +2347,7 @@ rb_mod_attr_writer(int argc, VALUE *argv, VALUE klass)
  *  (<code>@name</code>) and a corresponding access method to read it.
  *  Also creates a method called <code>name=</code> to set the attribute.
  *  String arguments are converted to symbols.
+ *  Returns an array of defined methods names as symbols.
  *
  *     module Mod
  *       attr_accessor(:one, :two)
@@ -2344,11 +2359,17 @@ static VALUE
 rb_mod_attr_accessor(int argc, VALUE *argv, VALUE klass)
 {
     int i;
+    VALUE names = rb_ary_new2(argc * 2);
 
     for (i=0; i<argc; i++) {
-	rb_attr(klass, id_for_attr(klass, argv[i]), TRUE, TRUE, TRUE);
+	ID id = id_for_attr(klass, argv[i]);
+	VALUE idv = ID2SYM(id);
+
+	rb_attr(klass, id, TRUE, TRUE, TRUE);
+	rb_ary_push(names, idv);
+	rb_ary_push(names, rb_str_intern(rb_sprintf("%"PRIsVALUE"=", idv)));
     }
-    return Qnil;
+    return names;
 }
 
 /*

spec/ruby/core/module/attr_accessor_spec.rb

@@ -67,6 +67,12 @@ describe "Module#attr_accessor" do
     Module.should have_public_instance_method(:attr_accessor, false)
   end
 
+  it "returns an array of defined methods names as symbols" do
+    Class.new do
+      (attr_accessor :foo, 'bar').should == [:foo, :foo=, :bar, :bar=]
+    end
+  end
+
   describe "on immediates" do
     before :each do
       class Fixnum

spec/ruby/core/module/attr_reader_spec.rb

@@ -61,4 +61,10 @@ describe "Module#attr_reader" do
   it "is a public method" do
     Module.should have_public_instance_method(:attr_reader, false)
   end
+
+  it "returns an array of defined methods names as symbols" do
+    Class.new do
+      (attr_reader :foo, 'bar').should == [:foo, :bar]
+    end
+  end
 end

spec/ruby/core/module/attr_spec.rb

@@ -145,4 +145,12 @@ describe "Module#attr" do
   it "is a public method" do
     Module.should have_public_instance_method(:attr, false)
   end
+
+  it "returns an array of defined methods names as symbols" do
+    Class.new do
+      (attr :foo, 'bar').should == [:foo, :bar]
+      (attr :baz, false).should == [:baz]
+      (attr :qux, true).should == [:qux, :qux=]
+    end
+  end
 end

spec/ruby/core/module/attr_writer_spec.rb

@@ -61,4 +61,10 @@ describe "Module#attr_writer" do
   it "is a public method" do
     Module.should have_public_instance_method(:attr_writer, false)
   end
+
+  it "returns an array of defined methods names as symbols" do
+    Class.new do
+      (attr_writer :foo, 'bar').should == [:foo=, :bar=]
+    end
+  end
 end