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Feature #2451

closed

BasicObject.initialize with variable number of argument

Added by marcandre (Marc-Andre Lafortune) over 14 years ago. Updated almost 13 years ago.

Status:
Closed
Target version:
[ruby-core:27080]

Description

=begin
If one wants to write a class easily extensible (for some kind of library, say), then there is no nice way to have the initialize method be extensible other than through monkeypatching.

This could be made much more flexible if BasicObject.initialize accepted any number of arguments.

Would there be a downsize to have BasicObject.initialize accept many arguments?

Here's a more detailed example:

class NiceClass
def initialize(arg1, arg2)
# do some stuff with arg1 and arg2
super # allow for included modules to initialize
end
end

Someone else:

class NiceClass
module CoolExtension
def initialize(arg1, arg2)
# do cool stuff
super # allow for more extensions
end
end

include CoolExtension
end

This would not work unless BasicObject#initialize accepts any number of arguments. Currently, only super() -- i.e. passing none of the arguments -- can be called, so arg1 & arg2 must be copied to instance variables for included modules to access, or else monkeypatching becomes the only possibility.

The patch is trivial:

diff --git a/object.c b/object.c
index 10eb983..33cae20 100644
--- a/object.c
+++ b/object.c
@@ -2538,7 +2538,7 @@ Init_Object(void)
#undef rb_intern
#define rb_intern(str) rb_intern_const(str)

  • rb_define_private_method(rb_cBasicObject, "initialize", rb_obj_dummy, 0);
  • rb_define_private_method(rb_cBasicObject, "initialize", rb_obj_dummy, -1);
    rb_define_alloc_func(rb_cBasicObject, rb_class_allocate_instance);
    rb_define_method(rb_cBasicObject, "==", rb_obj_equal, 1);
    rb_define_method(rb_cBasicObject, "equal?", rb_obj_equal, 1);

Notes:

  • There is no documentation for BasicObject#initialize.
  • Ironically, the Ruby Draft Specification states that Object#initialize accepts any number of arguments! I'm glad I already have that team agree with me ;-)
  • No error is generated by make test-all
  • See also http://blog.rubybestpractices.com/posts/rklemme/018-Complete_Class.html where Robert Klemme recommends calling super from constructors but has to use super(), i.e. passing no arguments

Similarly, I also propose that Object#initialize accepts any number of arguments in Ruby 1.8.8
=end


Related issues 1 (0 open1 closed)

Related to Ruby master - Bug #5542: Ruby 1.9.3-p0 changed arity on default initialization methodRejectedmarcandre (Marc-Andre Lafortune)11/02/2011Actions
Actions #1

Updated by matz (Yukihiro Matsumoto) over 14 years ago

=begin
Hi,

In message "Re: [ruby-core:27080] [Feature #2451] BasicObject.initialize with variable number of argument"
on Mon, 7 Dec 2009 10:18:36 +0900, Marc-Andre Lafortune writes:

|This could be made much more flexible if BasicObject.initialize accepted any number of arguments.
|Would there be a downsize to have BasicObject.initialize accept many arguments?

I don't think so. Please check in the fix.

						matz.

=end

Actions #2

Updated by marcandre (Marc-Andre Lafortune) over 14 years ago

  • Status changed from Open to Closed
  • % Done changed from 0 to 100

=begin
This issue was solved with changeset r26135.
Marc-Andre, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

=end

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