Feature #12041: Change the initializer of NameError to take a receiver as the third argument

• Status: Open
• Assignee: -
• Target version: -

[yuki24 (Yuki Nishijima)]

I would like to change NameError#initialize to take a receiver object as the third argument. An example would be like this:

receiver_object = Object.new
name_error      = NameError.new("Error message", "name", receiver_object)

name_error.receiver.equal?(receiver_object) # => true

The reason I wanted this change is Rails overrides Module#const_missing and raises an NameError without a receiver object. It has actually affected one of the did_you_mean's spell checkers and thus no suggestions for constant names will be made on Rails. One more use case I can think of is when there's a class that inherits from NameError or NoMethodError and an arbitrary receiver needs to be passed to the initializer of the class.

Please let me know if you have any thoughts.

[nobu (Nobuyoshi Nakada)]

What's about NoMethodError?
Currently, it is

NoMethodError.new(msg, name [, args])  #-> no_method_error

If NameError#initialize has third argument, where will it be placed?

The last?

NoMethodError.new(msg, name [, args [,receiver]])  #-> no_method_error

or same as NameError#initialize?

NoMethodError.new(msg, name [, receiver [, args]])  #-> no_method_error

A patch for the latter.

diff --git i/error.c w/error.c
index f88c19a..0ae9b58 100644
--- i/error.c
+++ w/error.c
@@ -1127,7 +1127,7 @@ rb_name_error_str(VALUE str, const char *fmt, ...)
 
 /*
  * call-seq:
- *   NameError.new(msg [, name])  -> name_error
+ *   NameError.new(msg [, name [, receiver]])  -> name_error
  *
  * Construct a new NameError exception. If given the <i>name</i>
  * parameter may subsequently be examined using the <code>NameError.name</code>
@@ -1138,8 +1138,10 @@ static VALUE
 name_err_initialize(int argc, VALUE *argv, VALUE self)
 {
     VALUE name;
+    VALUE recv;
     VALUE iseqw = Qnil;
 
+    recv = (argc > 2) ? argv[--argc] : Qundef;
     name = (argc > 1) ? argv[--argc] : Qnil;
     rb_call_super(argc, argv);
     rb_ivar_set(self, id_name, name);
@@ -1150,6 +1152,7 @@ name_err_initialize(int argc, VALUE *argv, VALUE self)
 	if (cfp) iseqw = rb_iseqw_new(cfp->iseq);
     }
     rb_ivar_set(self, id_iseq, iseqw);
+    if (recv != Qundef) rb_ivar_set(self, id_receiver, recv);
     return self;
 }
 
@@ -1192,7 +1195,7 @@ name_err_local_variables(VALUE self)
 
 /*
  * call-seq:
- *   NoMethodError.new(msg, name [, args])  -> no_method_error
+ *   NoMethodError.new(msg, name [, receiver [, args]])  -> no_method_error
  *
  * Construct a NoMethodError exception for a method of the given name
  * called with the given arguments. The name may be accessed using
diff --git i/test/ruby/test_exception.rb w/test/ruby/test_exception.rb
index 91732dd..e546988 100644
--- i/test/ruby/test_exception.rb
+++ w/test/ruby/test_exception.rb
@@ -699,6 +699,11 @@
     assert_equal(:foo, e.name)
     assert_same(obj, e.receiver)
     assert_equal(%i[a b c d e f g], e.local_variables.sort)
+
+    obj = Object.new
+    e = NameError.new("error", :foo, obj)
+    assert_equal(:foo, e.name)
+    assert_same(obj, e.receiver)
   end
 
   def test_name_error_info_parent_iseq_mark

[yuki24 (Yuki Nishijima)]

Speaking of NoMethodError, I think the former (NoMethodError.new(msg, name [, args [,receiver]])) makes more sense to me since the latter may break existing apps.

[nobu (Nobuyoshi Nakada)]

Nobuyoshi Nakada wrote:

or same as NameError#initialize?

NoMethodError.new(msg, name [, receiver [, args]])  #-> no_method_error

This was wrong.
The previous patch is:

NoMethodError.new(msg, name [[, receiver], args])  #-> no_method_error

[nobu (Nobuyoshi Nakada)]

https://github.com/ruby/ruby/compare/trunk...nobu:feature/12041-NameError%23initialize-recevier

[nobu (Nobuyoshi Nakada)]

I found this causes drb test failures, since NoMethodError now refers DRbObject and Marshal.dump fails.