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

5 May 2010

      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@lists.macosforge.org
http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel