Re: Template arg deduction
On Wednesday, 7 July 2021 at 19:14:52 UTC, Kevin Bailey wrote:
I'm trying to use some fairly simple template argument
deduction, but
maybe I'm not getting the syntax correct. C++ doesn't event
blink at
something like this, but D is giving me:
temptest.d(18): Error: template temptest.func cannot deduce
function from argument types !()(bar), candidates are:
temptest.d(10):func(T)(foo!T.bar f)
I guess D can't crack open a type like that?
```
template foo(T)
{
class bar
{
T t;
}
}
void func(T)(// 10
foo!(T).bar f)
{
}
int main()
{
foo!int.bar fi;
func(fi);// 18
}
```
This work:
```d
template foo(T){
class bar{
T t;
}
}
void func(alias F : foo!T, T)(F.bar f){
}
void main(){
foo!int.bar fi;
func(fi);
}
```
Re: Template arg deduction
On Wednesday, 7 July 2021 at 19:14:52 UTC, Kevin Bailey wrote:
I'm trying to use some fairly simple template argument
deduction, but
maybe I'm not getting the syntax correct. C++ doesn't event
blink at
something like this, but D is giving me:
temptest.d(18): Error: template temptest.func cannot deduce
function from argument types !()(bar), candidates are:
temptest.d(10):func(T)(foo!T.bar f)
I guess D can't crack open a type like that?
```
template foo(T)
{
class bar
{
T t;
}
}
void func(T)(// 10
foo!(T).bar f)
{
}
int main()
{
foo!int.bar fi;
func(fi);// 18
}
```
The following works:
```d
import std.stdio;
template foo(T)
{
class bar
{
T t;
}
}
void func(T) (// 10
T f) // No need to repeat
foo!(int).bar :)
{
}
int main()
{
foo!(int).bar fi;//brackets added, now syntax is
correct
func(fi);// 18. int couldn't get deduced here
return 0;
}
```
Re: Template arg deduction
On Wednesday, 7 July 2021 at 19:14:52 UTC, Kevin Bailey wrote: I'm trying to use some fairly simple template argument deduction, but maybe I'm not getting the syntax correct. C++ doesn't event blink at something like this, but D is giving me: temptest.d(18): Error: template temptest.func cannot deduce function from argument types !()(bar), candidates are: temptest.d(10):func(T)(foo!T.bar f) I guess D can't crack open a type like that? https://issues.dlang.org/show_bug.cgi?id=22111
Re: Template arg deduction
On 7/7/21 12:14 PM, Kevin Bailey wrote:
> fairly simple template argument deduction
It's not the simplest but it is still complicated. :)
> I guess D can't crack open a type like that?
There are other ways of achieving the same thing the simplest of which
is probably the following:
void func(B)(B f) {
}
Apparently, there are additional constraints on B, which can be
expressed in D with some flexibility, pragmatism, and optimism.
Ali
Template arg deduction
I'm trying to use some fairly simple template argument deduction,
but
maybe I'm not getting the syntax correct. C++ doesn't event blink
at
something like this, but D is giving me:
temptest.d(18): Error: template temptest.func cannot deduce
function from argument types !()(bar), candidates are:
temptest.d(10):func(T)(foo!T.bar f)
I guess D can't crack open a type like that?
```
template foo(T)
{
class bar
{
T t;
}
}
void func(T)(// 10
foo!(T).bar f)
{
}
int main()
{
foo!int.bar fi;
func(fi);// 18
}
```
