On Monday, 1 July 2024 at 13:00:55 UTC, ryuukk_ wrote:
please stick to what i wrote, i don't want string
concatenation, i provide a reduced example from my project,
everything should be a single template block, no extra
functions other than the append() one
Mixin templates are a declaration scope, not a function scope, so
they aren't necessarily analyzed top to bottom. This is why
allowing partial string mixins would be complicated, consider
this example:
```D
mixin template implement()
{
mixin("struct " ~ str);
mixin("{");
immutable string str = "T";
mixin("}");
}
```
It's not obvious how this should be compiled, and this is before
throwing `static if` and `static foreach` in the mix! If you want
to procedurally build a type in sequential steps, you'll have to
do that in a function scope.
If your concern is that such a function would add needless code
generation, you can use an immediately invoked anonymous function
like so:
```D
mixin template implement(string typeName, string[] members)
{
mixin(() {
string result = "struct " ~ typeName ~ " {";
foreach (name; members)
{
result ~= "int " ~ name ~ ";";
}
result ~= "}";
return result;
} ());
}
mixin implement!("S", ["x", "y", "z"]);
immutable s = S(x: 3, y: 5, z: 7);
```
You can use your fixed size array append function to try and
improve CTFE performance, but I'd start with straightforward
concatenation, and see if it's actually too slow. In that case,
maybe see if you can reduce it to a self-contained example and
post it on bugzilla as a performance bug.
