better error messages?

[slenkar]

when I try to use a null object I get the error SIGSEVD
is there a way of getting a more descriptive error message? such as 'object is nil'

[JSoftware]

Not really :)

You can get call traces by using the -gl compiler switch, and including sysutils somewhere. That way unhandled exceptions will print where it happened. You then have to figure out what happened. Segmentation faults can be hard to debug

The best way of handling such faults is to write proper OOP code ;)

[code_glitch]

Segmentation faults can be hard to debug

In my experience not can be but are extremely hard to solve... Its on the top 10 'I hate it when...' list. Put it this way: If I have a 2000 line program and I chose a program line at random there is around a 0.05% chance of it being the problematic one and it could take 2000 readln() statements or step-through commands to find it. Just imagine pressing <enter> 2,000 times to find the bug for each cycle of the program.

The last time it occurred to me like that I spent 1 hour debugging; The bug happened 35 seconds into a 40 cycle/sec program. As it turned out I finally fixed it by disabling some functions with my debug 'layer'. Basically, all functions have a Dbg_Off boolean variable. If its true, nothing occurs and return a preset value. If false (default) it does what its supposed to. It might take slightly longer to write but that approach gave me a 10min fix. And guess what: as it happened I didn't initialize Sdl or Ttf... ;) Isn't life nice sometimes. :)

[chronozphere]

I've found that "separation" is the key to attack these errors. You have to make sure that the buggy code can be tested separately. If its a hard bug to solve, you can write a new program with the sole purpose of testing a single class/module of your original program. :)

[WILL]

I've spent many an hour or event whole day stepping through my code to find those elusive memory segment errors. Clean and organized code will help, such as making all your objects and values easily accessible and keeping your arrays and lists organized in a similar fashion. (ie. try not to have similar arrays starting with both 1 and 0 if possible)

The only sure way to figure out one of these is to find the point in your program where the crash occurs, find this location in your code by adding break points to see if it crashes before it gets to the break point then step through your code until you find where your code and your stored values starts break down on your the way to intended your program to function. This can be an easy process or a difficult one depending on how you coded it.

Ultimately you should need your break points and evaluation tool for checking the value of your variables and other data.

[slenkar]

how do I add breakpoints?

when I get the breakpoint menu in lazarus 'source' is greyed out

freepascal only talks about the default IDE:http://www.freepascal.org/docs-html/user/usersu54.html

and the lazarus breakpoint doesnt mention my problem:http://wiki.lazarus.freepascal.org/IDE_Window:_Break_Points