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Re: Translate C++: 5-lines

Cross-posted to 2 groups.

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On 7.3.16 19:21, noSpam@gmail.com wrote:
> I don't want to learn C++, but this writer has some interesting ideas
> which I want to be able to understand:
> http://matt.might.net/articles/c++-template-meta-programming-with-l
> ambda-calculus/
>
> He writes:-- start extract --------------
>     The canonical example of compile-time computation is factorial in
>     templates:
> template <int N> <-following code is called a template. Where's the endToken?
> struct Factorial <-following code in "{}" is a structure/RECORD
> {
>    enum { value = N * Factorial<N-1>::value };
> };
>
> template <>
> struct Factorial<0>  <- yes we know: fact(0) == 1
> {
>    enum { value = 1 } ; <- but explain the syntax!
> };
>
>     Without the template specialization, a reference to
>     Factorial<4>::value would re-write itself forever, eventually
>     causing the template equivalent of a stack overflow.
>
>     Note the use of enumerations to force compile-time evaluation of the
>     member constant value.
>
>     With this template in place, code could refer to Factorial<4>::value
>     and get 24 computed at compile-time.
> ------------------------------ end of extract --------
> I 'come from' PASCAL..Oberon, rather than from C.
> The "<- arrows" are my guess at the C++ meanings.
> What means:  enum   -- in detail?
> Why use "< >" ?
> Does: "::" <token>      mean token is the functions return value?
>
> == TIA


Chris,

This has nothing to do with Raspberry Pi, and you're pretty
lazy so search the Web for answers yourself.

-- 

-TV

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Translate C++: 5-lines noSpam@gmail.com - 2016-03-07 17:21 +0000
  Re: Translate C++: 5-lines Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-03-07 20:04 +0200
    Re: Translate C++: 5-lines mm0fmf <none@invalid.com> - 2016-03-07 18:10 +0000
    Re: Translate C++: 5-lines noSpam@gmail.com - 2016-03-08 19:48 +0000
      Re: Translate C++: 5-lines Chick Tower <c.tower@deadspam.com> - 2016-03-09 18:11 +0000

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