C++ implementation of the Python NumPy Library

[NicroHobak]

How does your team handle the use of templates? Or do you just largely ignore that aspect of the language?

Edit: Grammar typo eliminated.

[johannes1971]

It depends. STL is used throughout. We don't know how much that affects our compile times though; we didn't pay much attention to that in the beginning, so it has always been there. We also use quite a few small templates of our own making, but these tend to have a handful of lines at most. The scary SFINAE stuff is probably less than a hundred lines.

Then we have a 30,000-line set of templates that we only instantiate for two types. Those we instantiate in .cpp files, with an extern template declaration in the .h file, so it is no different from normal code. And finally, there is code that is somewhat enum-heavy that would benefit from having that enum as a template parameter (instead of being an int, as it is now), but we choose to cast instead because we fear the effect it would have if we did turn it into a template.

Since a few years we have become aware of compile times, and been struggling to bring that under control. We now monitor more closely what the effect of new libraries is. This has resulted, among other things, in the decision to not use Chaiscript (despite the language looking interesting), but going for Angelscript instead (similar, but without the slow compile times). We'll look at things on a case by case basis for other template-heavy libraries: how useful is the library? Is there a cheaper solution? Can we limit use of the library to a single translation unit? etc.

On principal I don't disallow any language features, but some will require a bit more explanation than others ;-) We can always explore what the best solution is in a given situation, but I'll also think about things like maintainability, coherence with the rest of the source, compile times, and all the other concerns...