Unable to use NS* constants in NSObject subclass.

[alloye@…]

In tags/0.1/r89, attempting to use an NS* constant within an NSObject subclass results in a NameError. The same constants work fine in Object subclasses as illustrated below. I believe this behavior is unexpected as subclassing NSObject is a common pattern in Cocoa. The workaround of using Object may not be obvious to someone following Objective-C examples.

[~]: macirb --simple-prompt
>> framework 'Cocoa'
=> true
>> class Foo
>>   def mask
>>     NSShiftKeyMask
>>   end
>> end
=> nil
>> Foo.ancestors
=> [Foo, Object, NSObject, Kernel]
>> f = Foo.new
=> #<Foo:0x1841f10>
>> f.mask
=> 131072

[~]: macirb --simple-prompt
>> framework 'Cocoa'
=> true
>> class Bar < NSObject
>>   def mask
>>     NSShiftKeyMask
>>   end
>> end
=> nil
>> Bar.ancestors
=> [Bar, NSObject, Kernel]
>> b = Bar.alloc.init
=> #<Bar:0x18575d0>
>> b.mask
NameError: uninitialized constant Bar::NSShiftKeyMask
	from (irb):12:in `mask'
	from (irb):17
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:149:in `block (2 levels) in eval_input'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:262:in `signal_status'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:146:in `block in eval_input'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:145:in `eval_input'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:69:in `block in start'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:68:in `catch'
	from /Library/Frameworks/MacRuby.framework/Versions/0.1/usr/lib/ruby/1.9.0/irb.rb:68:in `start'
	from /usr/local/bin/macirb:12:in `<main>'

[lsansonetti@…]

The problem is that NSObject doesn't include Object in which the constants are defined.

But in MacRuby you should never have to subclass NSObject. Because all Ruby classes automatically inherit from NSObject.

$ macruby -ve "class Foo; end; p Foo.ancestors"
MacRuby version 0.2 (ruby 1.9.0 2008-03-01) [universal-darwin9.0]
[Foo, Object, NSObject, Kernel]

However we should still support this.

[alloye@…]

Perhaps it's an issue that can be addressed in the documentation. I have no problem deriving from Object, but there are many Objective-C examples in the world with objects that look like this:

@interface MyController : NSObject
    ...
@end

Someone converting to MacRuby might naturally guess they should do this:

class MyController < NSObject
  ...
end

[eloy.de.enige@…]

This is also definitely a problem for me with the RC layer, because obviously all RC code is NSObject subclasses, not Object.

[lsansonetti@…]

This is addressed in trunk. Inheriting from NSObject directory will raise a warning and automatically inherit from Object.

$ macirb 
>> framework 'Cocoa'
=> true
>> class Foo < NSObject
>>   def mask; NSShiftKeyMask; end
>> end
(irb):3: warning: Do not subclass NSObject directly, please subclass Object instead.
=> nil
>> Foo.new.mask
=> 131072