# Disconnecting signal\_connects before destroys **URL:** \ **Category:** Ruby-Gnome 2\ **Created:** [April 6, 2012, 1:06am UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618 "2012-04-06T01:06:09Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [April 6, 2012, 1:06am UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618/1 "2012-04-06T01:06:09Z")
So I have an applications I support that has been randomly crashing, but is also stuck at an old Ruby and Ruby/Gnome2 build. But my question should bypass that with “how should I do this, regardless of versions” My question is, basically, good form to destroy things you create, or rely on the garbage collector? Here’s the SegV problem I am having… So in my case, I am doing the following(yes, I know Canvas is depricated but this could apply to any GUI thing you do a signal\_connect on. spanPoly = Gnome::CanvasPolygon.new() spanPoly.signal\_connect(‘event’) do |item, event| end Ruby “randomly” is Seg Faulting with the following, (it does produce a very non helpful core file). somefile.rb:558: warning: instance variable holder not initialized somefile.rb:558: [BUG] Segmentation fault The line 558 is the signal\_connect line above. I add those objects to an array, and updated a view. At times they are destroyed. My guess at what is happening, is I have destroyed the object. But something is causing that signal\_connect handler to run, but crashes Ruby, as its been destroyed. The “instance variable holder not initialized” is a clue to me I think. In my code, should I really try to do a “signal\_handler\_disconnect” for that action before I destroy it? Like _Create it like this:_ spanPoly = Gnome::CanvasPolygon.new() spanPolyEventId = spanPoly.signal\_connect(‘event’) do |item, event| end _Destroy it like this:_ spanPoly.signal\_handler\_disconnect(spanPolyEventId) spanPoly.destroy() Is this maybe just good form? Trying to explicitly delete what you have “newed”. Thanks ---
**Author:** ![grantspeelman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/da6949/32.png) [@grantspeelman](https://www.ruby-forum.com/u/grantspeelman)\ **Post date:** [April 6, 2012, 4:36am UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618/2 "2012-04-06T04:36:10Z")
Hi Grant: In all the code I’ve written, I’ve never had to try to disconnect a signal. I don’t know what’s causing the seg fault error, but I know that I got a mysterious seg fault error when I was building a listview and didn’t provide a :text column. It made something in GTK go haywire, and everything behaved really strangely. It was very hard to locate the problem. So, I wouldn’t be surprised if the error is being caused elsewhere in your code. What other widgets are you using between the constructor and the destroy methods? You could try making the shortest possible example by eliminating all the code in between the constructor and destroy(), then start adding until you get the error. Hope it helps, Eric ---
**Author:** ![grantspeelman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/da6949/32.png) [@grantspeelman](https://www.ruby-forum.com/u/grantspeelman)\ **Post date:** [April 6, 2012, 9:40am UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618/3 "2012-04-06T09:40:10Z")
Subject: [ruby-gnome2-devel-en] Disconnecting signal\_connects before destroys Date: gio 05 apr 12 05:05:11 -0600 Quoting grant schoep ([removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)): > Ruby “randomly” is Seg Faulting with the following, (it does produce a > very non helpful core file). The core file is very useful! Install gdb, and do: gdb ruby then do bt and you will see the complete tree of function calls that led to the segfault. If you have compiled ruby-gnome yourself, and you have left symbols in your libraries, you will find indication to the program line in the C code that actually generated the segfault. If you do not see source file names and line numbers, you can always do export CFLAGS=“-O1 -g” then go to the ruby-gnome source tree and do make clean ruby extconf.rb make sudo make install and next time you segfault, GDB will show you source file and line number. You will also be able to inspect variable values at the moment the segfault has taken place. Carlo – - ``` Se la Strada e la sua Virtu' non fossero state messe da ``` parte, - K \* Carlo E. Prelz - [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) che bisogno ci sarebbe - ``` di parlare tanto di amore e di rettitudine? ``` (Chuang-Tzu) ---
**Author:** ![grantspeelman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/da6949/32.png) [@grantspeelman](https://www.ruby-forum.com/u/grantspeelman)\ **Post date:** [April 7, 2012, 3:08pm UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618/4 "2012-04-07T15:08:53Z")
I don’t know your code specifically and can not remember having used this Canvas variant. BUT, your error message sounds familiar. I remember I once had that when I compiled against some older GTK version. somefile.rb:558: warning: instance variable holder not initialized somefile.rb:558: [BUG] Segmentation fault Often enough, I had something like this there: foo.rb: (eval) warning I always thought that something in ruby-gtk is using a very large eval-style in order to call to C, or something like that. ---
**Author:** ![grantspeelman](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/da6949/32.png) [@grantspeelman](https://www.ruby-forum.com/u/grantspeelman)\ **Post date:** [April 7, 2012, 3:09pm UTC](https://www.ruby-forum.com/t/disconnecting-signal-connects-before-destroys/218618/5 "2012-04-07T15:09:34Z")
Carlo, That should be put on the wiki because it seems very useful. 🙂