- "std::map" - 2460
- "std::set" - 1574
- "std::list" - 393
The EQII codebase has nearly 3 million lines of just C/C++/C# (client, server, tools, not counting server lua script and data files) and uses STL containers liberally. If I had to do it all over again, I believe I'd forgo using STL containers for a few reasons:
- Memory Usage - STL allocators typically hold on to memory forever and reuse it as necessary. However, EQII has a very good memory manager with a constant-time free-able small block allocator (written by yours truly), reporting, leak detection, etc. Writing custom allocators for STL is a major pain (especially on an established codebase) and I'd really rather not hack STLport or the gnu implementation to use our memory manager.
- Compile Times - The more templated code you have the longer the compile and link times. I've talked previously about how we replaced std::vector with our own class to save compile times. Also, have you looked at STL implementation code? It's bloated and ugly, which brings me to my next point...
- Debugging - Trying to dig through a container in a debugger watch window (or GDB) is a pain. Sometimes it's even a matter of obscure memory offsets and you have to calculate addresses to see values in a map.
- Additional Functionality - If you have a vector that you're not using anymore and you want to free the memory for it,
clear()doesn't cut it. The code to do it is neither trivial nor intuitive:
std::vector< T >().swap( myVec ). Adding functions isn't easy as the STL containers are purposely non-virtual.
I'll probably look for a different solution for containers for my next project. Home-grown containers can emulate the STL containers and provide all that I desire above. They can even be compatible with STL functors and algorithms too.
Given how important memory management can be to fast execution, I'm surprised SOMEONE at SOE hasn't written a custom allocator yet.
Meyer's "Effective STL", items 10 and 11 (in the Containers section) seem to cover the gotchas. 10 even points to a couple samples with all the boilerplate code it says you'll need.
PS: One of the sample code URLs is to www.cuj.com, which is now camped by a domain squatter. The article has been moved to DDJ's site:
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