Re: Create constraint for each parameter in template arg pack
On Tuesday, 28 August 2018 at 13:05:15 UTC, bauss wrote:
I'm not sure if there is a better way, but isInstanceOf
(std.traits) seems to work with a static foreach and a static
if.
template Qwerty(Values...)
{
static foreach (value; Values)
{
static if (!isInstanceOf!(Qaz, value))
{
static assert(0, "Values are not Qaz only ...");
}
}
// ...
}
Thank you everybody!
Re: Create constraint for each parameter in template arg pack
On Tuesday, 28 August 2018 at 12:28:19 UTC, Andrey wrote:
Hello,
Let we have two variadic templates:
template Qwerty(Values...) {}
template Qaz(alias type, Data...) {}
Now I want to add a constraint to "Qwerty" so that each type in
"Values" pack must be a "Qaz" template. I don't care about
values of "type" or "Data" in "Qaz".
How to do it in D?
Generic solution:
template Qwerty(Values...)
if(allSatisfy!(isInstanceOf!Qaz, Values)){
}
class Qaz(alias type, Data...) {}
import std.meta : allSatisfy;
public import std.traits : isInstanceOf;
template isInstanceOf(alias T){
import std.traits : impl = isInstanceOf;
static enum isInstanceOf(alias X) = impl!(T, X);
static enum isInstanceOf(X) = impl!(T, X);
}
Re: Create constraint for each parameter in template arg pack
On Tuesday, 28 August 2018 at 13:05:15 UTC, bauss wrote:
On Tuesday, 28 August 2018 at 12:28:19 UTC, Andrey wrote:
Hello,
Let we have two variadic templates:
template Qwerty(Values...) {}
template Qaz(alias type, Data...) {}
Now I want to add a constraint to "Qwerty" so that each type
in "Values" pack must be a "Qaz" template. I don't care about
values of "type" or "Data" in "Qaz".
How to do it in D?
I'm not sure if there is a better way, but isInstanceOf
(std.traits) seems to work with a static foreach and a static
if.
template Qwerty(Values...)
{
static foreach (value; Values)
{
static if (!isInstanceOf!(Qaz, value))
{
static assert(0, "Values are not Qaz only ...");
}
}
// ...
}
https://dlang.org/phobos/std_traits.html#TemplateOf
maybe...
Re: Create constraint for each parameter in template arg pack
On Tuesday, 28 August 2018 at 12:28:19 UTC, Andrey wrote:
Hello,
Let we have two variadic templates:
template Qwerty(Values...) {}
template Qaz(alias type, Data...) {}
Now I want to add a constraint to "Qwerty" so that each type in
"Values" pack must be a "Qaz" template. I don't care about
values of "type" or "Data" in "Qaz".
How to do it in D?
I'm not sure if there is a better way, but isInstanceOf
(std.traits) seems to work with a static foreach and a static if.
template Qwerty(Values...)
{
static foreach (value; Values)
{
static if (!isInstanceOf!(Qaz, value))
{
static assert(0, "Values are not Qaz only ...");
}
}
// ...
}
Re: Create constraint for each parameter in template arg pack
On Tuesday, 28 August 2018 at 12:28:19 UTC, Andrey wrote:
Hello,
Let we have two variadic templates:
template Qwerty(Values...) {}
template Qaz(alias type, Data...) {}
Now I want to add a constraint to "Qwerty" so that each type in
"Values" pack must be a "Qaz" template. I don't care about
values of "type" or "Data" in "Qaz".
How to do it in D?
import std.meta : allSatisfy;
template Qwerty(Values...)
if(allSatisfy!(isQaz, Values)){
}
template Qaz(alias type, Data...) {}
enum isQaz(alias Q : Qaz!Args, Args...) = true;
enum isQaz(Args...) = false;
alias Foo = Qwerty!(Qaz!(i => i), Qaz!(i => i), Qaz!(i => i));
Create constraint for each parameter in template arg pack
Hello,
Let we have two variadic templates:
template Qwerty(Values...) {}
template Qaz(alias type, Data...) {}
Now I want to add a constraint to "Qwerty" so that each type in
"Values" pack must be a "Qaz" template. I don't care about values
of "type" or "Data" in "Qaz".
How to do it in D?
