On 12/05/2013 01:00 PM, Philippe Sigaud wrote:
> On Thu, Dec 5, 2013 at 9:17 PM, anonymous <[email protected]> wrote:
>> On Thursday, 5 December 2013 at 20:07:51 UTC, Uranuz wrote:
>
>>> How should I define value parameters inside "is" expression to make
code
>>> like this working?
>>
>>
>> is( N == Nullable!(T), T ... )
>
> Or
>
> is( N == Nullable!(T, nV), T, alias nV )
>
> Since nV is most probably an alias template parameter.
>
But none of those answer what I think the OP is asking: T must be a type
AND nV must be a value of that type.
I had thought the following to be true (especially the last quoted
sentence) [1]:
<quote>
is (T : Specifier, TemplateParamList)
is (T == Specifier, TemplateParamList)
is (T identifier : Specifier, TemplateParamList)
is (T identifier == Specifier, TemplateParamList)
These syntaxes allow for more complex cases. identifier may be omitted.
identifier, Specifier, :, and == all have the same meanings as described
above.
TemplateParamList is both a part of the condition that needs to be
satisfied and a facility to define additional aliases if the condition
is indeed satisfied. It works in the same way as template type deduction.
</quote>
If my the last sentence of mine is correct, then this is an
implementation problem as Uranuz's syntax should work. Although, I don't
see why my sentence would not be true. It definitely to be so in many
other uses.
Ali
[1] http://ddili.org/ders/d.en/is_expr.html
