Comments on: Mr. Bug Hunter

By: Derrick Barra

Derrick Barra — Sat, 20 Jun 2009 03:18:54 +0000

I’m still learning C# myself but I believe Val hit the needle on the head. Its just good coding practice to ensure that the pointers get deleted/reset once the memory location they are pointing to is empty.

By: Juuso

Juuso — Wed, 17 Jun 2009 03:29:40 +0000

Heh, actually, I considered putting BlitzMax as one additional vote option…

By: Leadwerks

Leadwerks — Tue, 16 Jun 2009 23:48:09 +0000

I don’t understand how you are even using Self in a function.

By: Val

Val — Tue, 16 Jun 2009 20:26:00 +0000

Yep, Sargon is correct. A piece of code that frees memory may or may not set the pointer(s) to NULL for performance reasons. It is typically good practice to do so to catch/avoid dangling pointer problems, but is not a requirement which is why it is important to know who is the owner of a piece of memory and to have a clear understanding of when the owner of that memory will potentially release it, and when it is safe to use. Use of dangling pointers are some of the nastiest bugs. :)

By: Lumooja

Lumooja — Tue, 16 Jun 2009 19:27:33 +0000

I cannot really vote, because I think it’s a bug in BlitzMax itself.

This would not have happened with C++, however you would have gotten many other wierd bugs (like particles not appearing) when running C++ in Debug mode :)

By: Sargon

Sargon — Tue, 16 Jun 2009 19:13:06 +0000

I think that blaming yourself is good practice in coding. ;)
Because only in rare cases its not your own fault.

By: Juuso

Juuso — Tue, 16 Jun 2009 19:07:13 +0000

Could be something like that… well, I guess I need to hear from Josh @ Leadwerks to see who here to blame.

(Not that I’d blame anyone, I’m really just one happy camper to see this thing solved)

By: Sargon

Sargon — Tue, 16 Jun 2009 18:53:02 +0000

Many times when you run a program, and you have an uninitialized pointer, it might point to the data that it used to point to when you ran the program the last time(and by now you have already terminated that run).
Its not exactly the same as in your case, but its an example how sometimes having data to which a pointer points to, doesn’t mean you are allowed to access that data.

By: Sargon

Sargon — Tue, 16 Jun 2009 18:49:26 +0000

The entity not being null, doesn’t mean the memory it pointed to was still allocated.
In matter of fact, sometimes when a pointer points to dynamic memory is freed, the data it pointed to is still there. It just isn’t suppose to be used, because somewhere it is marked as free, even though you can still access the data that used to be there.
I just wonder why it didn’t catch you are accessing unallocated memory, though this can happen as well.

By: Juuso

Juuso — Tue, 16 Jun 2009 18:23:55 +0000

Well, the funny thing is that the entity was usable after the loop. I could access to it, and it wasn’t null.

The thing that occured was that collisions of player controller got messy.

…It’s pretty darn hard to explain by text. Come here and I’ll show this to you (or video… hmm…). :)