Re: Newbie developer woes: segfault with custom data cell

[Fred Kiefer]

seigen wrote:
> Hello, I'm trying to port a simple Cocoa app (Transmission
> http://transmission.m0k.org/) to GNUstep.  I'm not very good at ObjC so
> keep that in mind.  I'm just looking for a pointer in the right
> direction.  I'm using Gorm and I've got the app more or less working in
> the backend, but while getting some information to the user via a
> custom NSTableView using custom data cell classes, it segfaults.  I've
> read around and I feel like I'm missing some critical step.  I've
> connected the table view to the controller object via delegate and
> datasource and set the custom data cell and custom tableview fields
> appropriately.  But can't figure out what to do next.  It started
> segfaulting when I changed the data cell classes to the custom ones and
> continues to even if I set them back.  According to GDB...
> 
> #0  0xb78fa46a in objc_msg_lookup () from /usr/lib/libobjc.so.1
> #1  0xb7a7a1f7 in -[NSUnarchiver decodeValueOfObjCType:at:] ()
>    from /usr/GNUstep/System/Library/Libraries/libgnustep-base.so.1.11

>From the backtrace you can tell that your applications segfaults during
NIB loading. Now if you did not implement achiving for your custom class
yourself, it should not be something you have to worry about.
Best you send us your Gorm file and I or Gregory have a look. As a
workaround I would suggest that you try with building up a new Gorm
file, as the one you are using is in some way corrupt.

I tried to load the original NIB file with GNustep, we have a
preliminary Cocoa keyed NIB file loading implementation. But this failed
here, as we don't have an implementation for NSClassSwapper and I was
not able to write one, as the NSKeyedUnarchiver class does lack the
method replaceObject:withObject:, present in NSUnarchiver. No idea why
Apple did this and how they work around this themselves.

Fred