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From: Hyman Rosen <hyrosen@mail.com>
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Subject: Re: why learn C?
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Date: Fri, 06 Apr 2007 22:16:35 GMT
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Date: 2007-04-06T22:16:35+00:00
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Ray Blaak wrote:
> it is still the case that "programming" like this with templates
 > is fundamentally strange. One has to think very differently compared
 > to the usual programming languages.

It is a declarative style involving immutable objects and pattern
matching. I understand that this is similar to the way functional
programming languages work in some respects. Thinking differently
isn't necessarily a flaw, either.

> If you really want to test a prime, for example, why on earth
> would you not do so at run time, when you actually need the value?

Because in C++, these values direct the compiler into different
code-generation pathways, allowing the generation of code that is as
efficient as if plain constants had appeared in the code. This is
generative programming, as expounded by Czarnecki & Eisenecker.

> The proper way to program at compile time should be with traditional
 > program statements that happen to run in the "build" phase.

C++ happened to find itself in a position where compile-time programming
became possible through a happy accident, and that has led to where it
is today. There are people working on more straightforward approaches to
this, and if they work out, they may make it into C++.