Re: check instance of nested variadic template
On Saturday, 5 November 2016 at 13:43:34 UTC, Lodovico Giaretta wrote: On Saturday, 5 November 2016 at 13:34:51 UTC, Gianni Pisetta wrote: When i have time i will test it with ldc and see if the result is the same, then it will probably be a front-end bug and i will report it as an issue. I think it has already been reported. https://issues.dlang.org/show_bug.cgi?id=13372 Yes. Though the report is more generalized now. It applies to any eponymous type template.
Re: check instance of nested variadic template
On Saturday, 5 November 2016 at 14:37:53 UTC, Basile B. wrote:
On Saturday, 5 November 2016 at 13:34:51 UTC, Gianni Pisetta
wrote:
[...]
Indeed, I've been fighting against that since a few minutes. We
cant select the Base of an eponymous template.
template isEponymousTemplate(T)
{
static if (is(T == class) || is(T == interface) || is(T ==
struct) || is(T == union))
{
enum p = __traits(parent, T).stringof == T.stringof;
enum isEponymousTemplate = p && isTemplateInstance!T;
}
else
enum isEponymousTemplate = false;
}
template TemplateBase(T : Base!Args, alias Base, Args...)
if (is(T == class) || is(T == interface) || is(T == struct) ||
is(T == union))
{
alias TemplateBase = Base;
}
To be more accurate the template base can be selected for
template A(T) {class A{}}
but not for
class A(T){}
Re: check instance of nested variadic template
On Saturday, 5 November 2016 at 13:34:51 UTC, Gianni Pisetta
wrote:
When i have time i will test it with ldc and see if the result
is the same, then it will probably be a front-end bug and i
will report it as an issue.
Indeed, I've been fighting against that since a few minutes. We
cant select the Base of an eponymous template.
template isEponymousTemplate(T)
{
static if (is(T == class) || is(T == interface) || is(T ==
struct) || is(T == union))
{
enum p = __traits(parent, T).stringof == T.stringof;
enum isEponymousTemplate = p && isTemplateInstance!T;
}
else
enum isEponymousTemplate = false;
}
template TemplateBase(T : Base!Args, alias Base, Args...)
if (is(T == class) || is(T == interface) || is(T == struct) ||
is(T == union))
{
alias TemplateBase = Base;
}
Re: check instance of nested variadic template
On Saturday, 5 November 2016 at 13:34:51 UTC, Gianni Pisetta wrote: When i have time i will test it with ldc and see if the result is the same, then it will probably be a front-end bug and i will report it as an issue. I think it has already been reported. https://issues.dlang.org/show_bug.cgi?id=13372
Re: check instance of nested variadic template
When i have time i will test it with ldc and see if the result is the same, then it will probably be a front-end bug and i will report it as an issue.
Re: check instance of nested variadic template
On Friday, 4 November 2016 at 17:37:10 UTC, Basile B. wrote:
Hello, I'm not sure that's exactly what you want but check this:
template A(As...) {
template B(Bs...) {
}
}
alias BI = A!(1,2).B!(3,4,5);
import std.traits;
template NestedTemplateArgsOf(alias T)
{
alias NestedTemplateArgsOf =
TemplateArgsOf!(__traits(parent, T));
}
alias Bs = TemplateArgsOf!BI;
alias As = NestedTemplateArgsOf!BI;
static if (is(typeof(BI) == typeof(A!As.B!Bs)))
{
pragma(msg, "for the win");
}
The missing key was NestedTemplateArgsOf. With it you can solve
the problem.
Well, kind of. But i think i can make it with what i got from
your example, so thanks.
Another thing that I encountered and while messing with your code
is that __traits( parent, T ) does not work as expected when you
have structs instead of template. I think because something like
struct A(As...) {}
is downgraded to
template A(As...) {
struct A {}
}
when i use __traits( parent, A!(1,2) ) i get in return A!(1,2),
looping around the same symbol.
When you compile this
struct A(As...) {}
import std.conv;
pragma( msg, "The parent symbol is the same? " ~ to!string(
__traits( isSame, A!(1,2), __traits( parent, A!(1,2) ) ) ) );
void main() {}
you get a really interesting result:
The parent symbol is the same? true
Gianni Pisetta
Re: check instance of nested variadic template
On Friday, 4 November 2016 at 17:37:10 UTC, Basile B. wrote: On Friday, 4 November 2016 at 15:50:36 UTC, Gianni Pisetta wrote: Hi all, I am having issues finding a solution for this, i want to check if an alias is an istance of a variadic template nested in another variadic template. [...] there is some sort of workaround? Thanks, Gianni Hello, I'm not sure that's exactly what you want but check this: [...] A better generic solution: https://github.com/BBasile/iz/blob/1a6452b376a3a1977c8287f9ef294d2dde76952d/import/iz/types.d#L398
Re: check instance of nested variadic template
On Friday, 4 November 2016 at 15:50:36 UTC, Gianni Pisetta wrote:
Hi all,
I am having issues finding a solution for this, i want to check
if an alias is an istance of a variadic template nested in
another variadic template.
[...]
there is some sort of workaround?
Thanks,
Gianni
Hello, I'm not sure that's exactly what you want but check this:
template A(As...) {
template B(Bs...) {
}
}
alias BI = A!(1,2).B!(3,4,5);
import std.traits;
template NestedTemplateArgsOf(alias T)
{
alias NestedTemplateArgsOf = TemplateArgsOf!(__traits(parent,
T));
}
alias Bs = TemplateArgsOf!BI;
alias As = NestedTemplateArgsOf!BI;
static if (is(typeof(BI) == typeof(A!As.B!Bs)))
{
pragma(msg, "for the win");
}
The missing key was NestedTemplateArgsOf. With it you can solve
the problem.
check instance of nested variadic template
Hi all,
I am having issues finding a solution for this, i want to check
if an alias is an istance of a variadic template nested in
another variadic template.
Here is an example:
template A(As...) {
template B(Bs...) {
}
}
alias BI = A!(1,2).B!(3,4,5);
Now i want to test if BI is an istance of A.B, but i can't do
something like this:
static if ( is( BI == A!As.B!Bs, As..., Bs... ) ) {
// Do Something
}
there is some sort of workaround?
Thanks,
Gianni
