Re: No templates for performance?

Scott Lurndal <scott@slp53.sl.home> wrote:


And the alternative is what, exactly?

Writing the functions for each separate type manually? Exactly how would this
be different from the template (other than the template avoiding code
repetition)?

Making the same code support different types? And how exactly would this be
achieved? I see only two possibilities:

1) OO polymorphism, which isn't possible without RTTI (which was also banned
in that list) and would actually increase memory consumption by a significant
lot (because now objects would need to be heap-allocated).

2) Bypass type safety mechanisms and make the code handle things like void
pointers and such. Yeah, great solution. (Not only is it completely horrible
and unsafe code, it also cannot handle everything that a template can, and
in a much safer way at that.)

Religiously avoiding templates is actually detrimental to the quality of
the code and may, in fact, in some cases produce *less* efficient code
(in terms of speed and/or memory usage).

Fearing that caches will fill up quicker if templates are instantiated with
lots of types is also quite moot in most cases. Just because the executable
binary may get larger (which isn't actually always the case) doesn't mean
that caches fill up faster. The CPU only loads into the cache code that is
being run.