Is metaprogramming useful?

[Sean Kelly]

Just a few corrections, as I was still waking up when I wrote this.

Sean Kelly wrote:
> Frank Benoit (keinfarbton) wrote:
>>
>> 1.) Is metaprogramming really useful or only kind of hype?
> 
> In-language code generation has an advantage over using a standalone 
> preprocessor to perform the same task.  And generated code has the 
> potential to contain fewer bugs than hand-written code, as well as 
> reduce coding time for a project.  Finally, template code in general 
> combined with common optimizer techniques can result in extremely fast 
> code because it is essentially equivalent to hand-optimized code in many 
> cases.

Equivalent to or better than.  Inlining is a huge part of why template 
code is as fast as it is, and even hand tuning typically results in 
little manually inlined code--it's too difficult to maintain.

> How fast?  Bjarne did a presentation at SDWest regarding some 
> real-world applications where C++ was shown to outperform hand-tuned C 
> and even FORTRAN by an order of magnitude for numeric calculations, and 
> the reason was entirely attributed to the extensive use of template 
> code.

I believe it actually outperformed hand-tuned C by an order of magnitude 
and FORTRAN by a smaller margin, but it was still faster.  Bjarne 
attributed the results to templates, but inlining obviously played a 
huge part.


Sean