Re: Avoiding C++ Templates In Cipher Implementation

From: Benjamin Goldberg (ben.goldberg_at_hotpop.com)
Date: 06/13/03 

Date: Thu, 12 Jun 2003 21:14:42 -0400

Ernst Lippe wrote:
[snip]
> Many people see templates as a form of glorified macro's. Even though
> I am not a great fan of macro's I have to admit that their semantics
> are not really difficult. Macro's can be described as a simple textual
> operation on your source text that can then be used in the next phases
> of the compilation. Templates are completely different, unlike macro's
> it is not possible to write a simple program that removes the
> templates from your program and gives you back a semantically
> equivalent template-free program. In theory it may be possible to
> write such a program,

In theory, any cfront-style C++ compiler is such a program :)

Alas, in practice, many of them have *very* incomplete template
handling... last that I heard, anyway. My knowledge on this is quite
dated, though, and there may exist a more complete cfront compiler.

> but because templates are turing complete you
> cannot guarantee that this program will always terminate.

Isn't this true even with a regular C++ compiler?

Out of curiosity, what happens if you write a program which has:

   template <int i> struct foo;
   template <int i> { struct foo<i+1> bar; };
   int main(int argc, char *argv[]) {
      foo<0> quux;
      return 0;
   }

With a normal (non-cfront) C++ compiler, what happens? 

-- 
$a=24;split//,240513;s/\B/ => /for@@=qw(ac ab bc ba cb ca
);{push(@b,$a),($a-=6)^=1 for 2..$a/6x--$|;print "$@[$a%6
]\n";((6<=($a-=6))?$a+=$_[$a%6]-$a%6:($a=pop @b))&&redo;}

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