Backport #4273
closedInherited hook called after module_eval for Class.new
Description
=begin
class Base
def self.inherited(klass)
klass.instance_variable_set(:@x, :base)
end
end
Derived = Class.new(Base) do
@x = :derived
end
BUG HERE!¶
Derived.instance_variable_get(:@x) #=> :base
In Ruby 1.9 the line above returns :derived. Ruby 1.9 has the expected behaviour as the inherited hook should be invoked prior to running the block -- so that the block can override any ivar defaults defined by the inherited hook.
The problem lies in the following code, from object.c:
static VALUE
rb_class_initialize(argc, argv, klass)
int argc;
VALUE *argv;
VALUE klass;
{
VALUE super;
if (RCLASS(klass)->super != 0) {
rb_raise(rb_eTypeError, "already initialized class");
}
if (rb_scan_args(argc, argv, "01", &super) == 0) {
super = rb_cObject;
}
else {
rb_check_inheritable(super);
}
RCLASS(klass)->super = super;
rb_make_metaclass(klass, RBASIC(super)->klass);
- rb_mod_initialize(klass);
- rb_class_inherited(super, klass);
return klass;
}
The fix would be simple, just swap the two starred lines above.
thanks,
John
=end
Updated by zimbatm (zimba tm) almost 14 years ago
=begin
Hi,
unfortunately, changing these two lines would break backward-compatibility, which would bring the same situation between the 1.8.7 release and the next-one. The only solutions I see for you is to either not rely on that feature, either discard 1.8 backward-compatibility.
I added this problem to this page that I just created : http://redmine.ruby-lang.org/wiki/ruby-19/MigrationIssuesFrom18
Cheers,
zimbatm
=end
Updated by jeremyevans0 (Jeremy Evans) over 5 years ago
- Tracker changed from Bug to Backport
- Project changed from Ruby 1.8 to Backport187
- Description updated (diff)
- Status changed from Open to Closed
- Target version deleted (
Ruby 1.8.7) - ruby -v deleted (
ruby 1.8.7 (2010-06-23 patchlevel 299) [i386-mingw32])