On Tuesday, 16 July 2013 at 04:37:33 UTC, Ali Çehreli wrote:
On 07/15/2013 08:43 PM, JS wrote:
> http://dpaste.dzfl.pl/7c8b0ba9
>
> Why the heck can't we use integers in ctfe's? There seems to
be no
> simple way to create a counter and this is one of the most
basic
> programming constructs to use.. yet with ctfe's it's
impossible.
>
> I'd like each variable in the nested structs to be
incremented properly.
I did not read the code but just from your description, the
separate compilation model that D uses would preclude that. For
example, compilation of a.d would not know anything about the
counter that b.d has counted during its compilation.
Ali
Huh? what is a.d and b.d?
The template transforms a string into a D code string... which is
then string mixed in. The counter and code generation have
nothing to do with the result. A counter is needed in the
generation of the code to generate enum like characteristics.
It does use recursion, and I could pass a variable that counts
the number of elements but this too would probably not work due
to D bitching about using ints.
I imagine one could hack D to make it's flawed CTFE system work,
to some degree... like using strings:
template inc(string s)
{
string _(string a)
{
if (a == "0") return "1";
if (a == "1") return "2";
if (a == "2") return "3";
if (a == "3") return "4";
return "0";
}
enum inc = _(s); pragma(msg, ":"~_(s));
}
which is a modulo 4 incrementer. So, CTFE's have the ability to
count... but extremely short sighted that they don't. I imagine
can write a whole template library using strings to emulate ints
in ctfe's... what a shame though...
