[MacRuby-devel] How do I subclass Obj-C classes in MacRuby?

[Thibault Martin-Lagardette]

Hi!

I believe the problem is that you were overriding the wrong init method. Here is what I changed to your code to make it work:

class MyNode < ODNode
    def initWithSession(session, name:name, error:err)
        if super
            @session = session
            self
        end
    end
end

session = ODSession.defaultSession
node = MyNode.nodeWithSession session, name: "/Local/Default", error: nil

I override initWithSession:name:error instead of init, and created a "MyNode" object the exact same way I would have created an ODNode :-)
The results were, I believe, what you would expect:

$> macruby od.rb 
{"dsAttrTypeStandard:AppleMetaNodeLocation"=>["/Local/Default"], ...}

Hope that helps!

-- 
Thibault Martin-Lagardette



On May 4, 2010, at 23:37, russell muetzelfeldt wrote:

> Hi All,
> 
> I've produced an ugly bunch of ruby that talks to OpenDirectory and am trying to clean it up a bit. Currently I'm using pure ruby classes that proxy Obj-C objects held in instance variables, but my goal is to have something structured like this -
> 
> module OpenDirectory
>  class Node < ODNode
>    def find_user_by_name name
>      ...
>    end
>  end
> end
> 
> but I can't work out how to make a Ruby class that subclasses an Obj-C class and overrides the initialiser. With classes that descend from Obj-C classes the ruby "initialize" method doesn't seem to get called (because they're missing descent from the Ruby base Object class?), and all my attempts to override init result in
> 
> 2010-05-05 15:55:34.237 macruby[2600:903] object 0x200249900 with 0 retain-count passed to CFMakeCollectable.
> 
> and a segfault.
> 
> Attached below is a reduced case, if anyone can point out how to get a valid MyNode object it'd be much appreciated. If node is a real ODNode (as in the commented lines) all works correctly. I'm not calling super, since the object has (I believe) already been alloc'd and I'm explicitly calling the designated initializer later in my own init. If I *do* call super in my own init, I just get an additional "object 0x... with 0 retain-count passed to CFMakeCollectable" error. If I use ODNode.nodeWithSession:name:error: in my own init the example below works, but I end up with an ODNode rather than a MyNode so it's missing any methods I'm adding to my own class.
> 
> (I'm also unsure whether I need to be retaining the session in an instance variable myself or if it's also being retained in the ODNode, but that's another question.)
> 
> Any pointers very much appreciated...
> 
> Russell
> 
> 
> example:
> 
> 
> framework 'OpenDirectory'
> 
> # no BridgeSupport for CFOpenDirectory.framework... :(
> Users = "dsRecTypeStandard:Users"
> RecordName = "dsAttrTypeStandard:RecordName"
> MatchEqualTo = 0x2001
> RealName = "dsAttrTypeStandard:RealName"
> 
> # some account name to search for
> me = "russm"
> 
> class MyNode < ODNode
>  def init
>    @session = ODSession.defaultSession
>    STDERR.puts "===== pre CFMakeCollectable error"
>    self.initWithSession @session, name:"/Local/Default", error:nil
>    STDERR.puts "===== post CFMakeCollectable error"
>    self
>  end
> end
> 
> node = MyNode.new
> #session = ODSession.defaultSession
> #node = ODNode.nodeWithSession session, name:"/Local/Default", error:nil
> query = ODQuery.queryWithNode node,
>  forRecordTypes: Users,
>  attribute: RecordName,
>  matchType: MatchEqualTo,
>  queryValues: me,
>  returnAttributes: RealName,
>  maximumResults:0,
>  error:nil
> STDERR.puts "===== pre segfault"
> results = query.resultsAllowingPartial false, error:nil
> STDERR.puts "===== post segfault"
> result_attributes = results[0].recordDetailsForAttributes nil, error:nil
> puts result_attributes.inspect
> 
> _______________________________________________
> MacRuby-devel mailing list
> MacRuby-devel at lists.macosforge.org
> http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.macosforge.org/pipermail/macruby-devel/attachments/20100505/abdea144/attachment-0001.html>