On Saturday, 25 May 2013 at 10:46:05 UTC, Ahuzhgairl wrote:
Hi,
In D, the : in a template parameter list only binds to 1
parameter.
There is no way to specialize upon the entire template
parameter list.
Therefore you can't do much with the pattern matching and it's
not powerful.
Not a reasonable situation for a language aiming to be only the
best.
What is needed is the ability to bind to the whole template
parameter list:
template <class> struct get_class;
template <class R, class C, class... A> struct get_class<R
(C::*)(A...)> { typedef C type; };
Let's shorten the terms:
<R, C, A...> @ <R (C::*)(A...)>
And here's how this kind of specialization would work in D:
template A[B] { struct C {} } template Foo[alias X, Y, Z @
X[Y].Z] { alias Z Foo; } void main() { alias Foo[A[bool].C]
xxx; }
You need a separate delimiter besides : which does not bind to
individual parameters, but which binds to the set of parameters.
I propose @ as the character which shall be the delimiter for
the arguments to the pattern match, and the pattern match.
On an unrelated note, I don't like the ! thing so I use [].
Sorry for the confusion there.
z
Hi, I obviously don't know D that much, but I assume I do.
I have this feature that I can't even show a working example that
exists in C++. I also can't come up with any use case, but I know
this is mandatory to have.
As I assume I know D well enough, I assume I know that this is
impossible in D, so I propose an improvement.
With that improvement, a new syntax is introduced to support some
new feature that is barely defined and it can be used in unknown
situation.
I also explain myself using my own made up syntax. I don't care
if it conflict with other language construct as it is superior
anyway.
