Memory management dilemma

[Rémy Mouëza]

In article <e5c89d$6ki$2 at digitaldaemon.com>, Jeff Parsons says...
>I need to manage memory explicitly since it seems to be impossible to 
>guarantee long-term smooth operation when using only garbage collection. 
>I don't see introducing artificial pauses into gameplay during which 
>garbage is collected, or allowing the game to bloat horribly over time 
>as solutions.

I discussed about similar concerns with a friend of mine: is a C programmer and
think nothing is better than C. He discovered that D is binary compatible with C
and we're planning to collaborate on a game engine. Memory management was (and
might still be) the first problem we needed to solve. 

>[*] I can see a LOT of manual "delete whatever" popping up if I'm 
>dealing with expressions that involve a lot of vector or matrix math. Is 
>there a way to avoid this (having locally created objects automatically 
>destroyed when they go out of scope)?

Yes, there is a way: auto variable.
#   Result aFunction ()
#   {
#       auto Matrix matrix = new Matrix ;
#       // ... work with your matrix
#       return result ;
#   }
#   // getting out of scope deletes 
#   // the auto allocated matrix.

You can also make an auto class : 
auto class Matrix { ... }
All the instances of this class will be deleted when getting out of scope.
There are restriction in the use of auto variable : you can't return an auto
variable and... I've forgotten, they're due to the temporary nature of such
instances. See:
http://www.digitalmars.com/d/declaration.html#AutoDeclaration
http://www.digitalmars.com/d/class.html#deallocators, the section after
deallocators deals with auto classes.

There is also the scope ( exit ) {} statement that defer the execution of its
instructions at the exit of the current scope.
http://www.digitalmars.com/d/statement.html#scope
Less convenient than the auto variable.

>Is there a nice neat way to handle this in D or should I expect a lot of 
>pain when not using the garbage collector? And if I do go down this 
>path, how can I tell if I -am- leaking memory?
People says lot of good things about Valgrind, a software that trace your memory
allocations. I don't know if it works for D.