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by deadgrey19 3743 days ago
<shameless self promotion> Take a look at this instead. Work started on this before C-generics came about, so there is pretty heavy macro usage, but all data structures are type safe: https://github.com/mgrosvenor/libchaste
1 comments
vc98mvco 3743 days ago
I see you use C macro templates. I have been experimenting with containers that use those. The advantages are speed and full type safety, and disadvantages are long compilations times (which have to be done only once though), the need to define a new template for every type in (only one) separate file, code bloat, and somewhat long function names (I don't use member function pointers).

I'm not sure if all that is worth it.

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deadgrey19 3743 days ago
I've not noticed the compile time increase to be honest. But I have noticed the type safety. A few times it has saved me from bugs that would have taken days to find if I was using void* casts. In my world (mostly high perf networking) I'm happy to pay a (small ~= unnoticeable) compile time cost if I get both safety and performance.

To make it more user friendly, I've provided (yet more) macros to make defining new types super easy. Using the macros does not necessarily involve adding a separate file, although the code is much cleaner if you do. And I don't have anything against adding extra files. There's almost no cost to me. I often group a couple of vectors or linked lists into a single .c/.h file pair to keep things manageable.

The code bloat you get is on par with using C++ templates. In fact, I'd say that it is probably better because the type safe macro's all devolve to a void* underlying implementation rather than generating separate instances. So it's pretty thin. You can always throw away the standard types list that I provide so that you don't have to pay for anything you don't use. And if you really want to, you can interface to the void* underlying implementation directly, loose the indirection costs, the function pointers and the macro costs. Basically, you can choose which world you want to live in, or live in both at the same time.

The long function names are handled by macros again. And since i used function pointer indirection you almost never see them. The costs with this sort of thing are minimal. A typical invocation looks something like

  CH_VECTOR(MYVECCLASS)* myvec =  NEW_CH_VECTOR(MYVECCLASS);
  myvec->append(myvec,object);
There are certainly tradeoffs, the implementation is not nearly as mature as I'd like and debugging problems inside the containers is a HUGE PITA. But in my experience it lets me kee the benefits of working in C (can pull inside the kernel, can port to different machines, easy control over memory and performance) and gives me the flexibility of doing higher level things when I want.
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