Memoization in compile-time

[weaselcat via Digitalmars-d-learn]

On Friday, 13 March 2015 at 13:16:27 UTC, weaselcat wrote:
> On Friday, 13 March 2015 at 12:49:48 UTC, Dennis Ritchie wrote:
>> On Friday, 13 March 2015 at 02:38:18 UTC, Rikki Cattermole 
>> wrote:
>>> You could assign it to e.g. an enum. Or force it over using 
>>> meta-programming.
>>
>> And this code can be rewritten to D?
>>
>> template <int n>
>> struct Factorial
>> {
>>    enum { value = n * Factorial<n - 1>::value };
>> };
>>
>> template <>
>> struct Factorial<0>
>> {
>>    enum { value = 1 };
>> };
>>
>> int main()
>> {
>>    constexpr auto x = Factorial<5>::value;
>>    constexpr auto y = Factorial<7>::value;
>> }
>
> confusingly, D uses enum for named compile-time constants.
> http://ddili.org/ders/d.en/enum.html
>
> If you take Rikki's example and apply it to an enum(i.e,
> enum x = factorial(5);
> )
>
> the program will fail to compile if it can't be computed at 
> compile-time.

woops, walked away to get coffee before I submitted and got
beaten to the punch by a better answer : )