Re: "is not an lvalue" when passing template function to spawn function

[Bienlein via Digitalmars-d-learn]

On Thursday, 9 November 2023 at 09:40:47 UTC, Bienlein wrote:
On Wednesday, 8 November 2023 at 16:47:02 UTC, Paul Backus 
wrote:
On Wednesday, 8 November 2023 at 16:30:49 UTC, Bienlein wrote:
...
The actual problem here is that you can't take the address of 
a template without instantiating it first. To make your 
example work, replace `&addToBiz` with `&addToBiz!int`, like 
this:

    spawn(&addToBiz!int, biz);

Thanks, Paul. This helped a step further. When applying your 
change it looks like this:

Biz!int biz = new Biz!int(123);
spawn(&addToBiz!int, biz);

Then I get this error: 'Error: static assert:  "Aliases to 
mutable thread-local data not allowed."'

For this error I found this in the Internet: 
https://stackoverflow.com/questions/14395018/aliases-to-mutable-thread-local-data-not-allowed

But this change, did not help:

spawn(&addToBiz!int, cast(shared) biz);

Then I moved "Biz!int biz = new Biz!int(123);" out of the main 
function. Compiler complains about static this. Okay, then the 
code outside the main function now looks this way:


class Biz(T) {

    private T value;

    this(T value) {
        this.value = value;
    }

}

static void addToBiz(T)(Biz!T biz)
{
    // ...
}


Biz!int biz;

static this() {
    biz = new Biz!int(123);
}



int main()
{
   // ...
}

However, this results in no gain as the compiler now shows the 
initial error again: 'Error: static assert:  "Aliases to 
mutable thread-local data not allowed."'

Everything I tried on my own was also to no avail. If someone 
could gould give me a hint again ... ;-)

Thank you.

If I supply a callback function with the parameter not being an 
instance from a parameterized class I get the same error. The 
problem seems to be that the parameter of the callback function 
takes on object as a parameter and not a built-in type like int 
or String.

The samples on how to use the spawn function on dlang.org does 
not contain a sample on how to get things to work with a objecgt 
being supllied as parameter to the callback function