On Monday, 23 May 2022 at 15:14:53 UTC, Vindex wrote:
I have this code:
```
import std.array, std.exception, std.stdio;
mixin template RealizeException() {
this(string msg, string file = __FILE__, size_t line =
__LINE__) {
super(msg, file, line);
}
}
class WrongUsage : Exception {
mixin RealizeException;
this(string[] messages, string file = __FILE__, size_t line
= __LINE__) {
auto msg = std.array.join(messages, "\n");
super(msg, file, line);
}
}
void main() {
throw new WrongUsage("Error message.");
}
```
... and this error:
```
mixin_exception.d(19): Error: constructor
`mixin_exception.WrongUsage.this(string[] messages, string file
= __FILE__, ulong line = cast(ulong)__LINE__)` is not callable
using argument types `(string)`
mixin_exception.d(19): cannot pass argument `"Error
message."` of type `string` to parameter `string[] messages`
Failed: ["/usr/bin/dmd", "-v", "-o-", "mixin_exception.d",
"-I."]
```
Why? Why can't I have two constructors when I use mixin?
If I replace mixin to real code, I have no problem:
```
class WrongUsage : Exception {
this(string msg, string file = __FILE__, size_t line =
__LINE__) {
super(msg, file, line);
}
this(string[] messages, string file = __FILE__, size_t line
= __LINE__) {
auto msg = std.array.join(messages, "\n");
super(msg, file, line);
}
}
```
mixin template create scope, for example if it was normal
function (no ctor), you can do this:
```d
mixin template RealizeException() {
static void foo(string){}
}
class WrongUsage{
mixin RealizeException x;
alias foo = x.foo;
static void foo(string[]){}
}
void main() {
WrongUsage.foo("Error message.");
}
```
But for ctor this doesn't work...
