Hello,

> void test(const ref string[3] qazzz) { qazzz.writeln; }
> 
> void main()
> {
>     enum string[3] value = ["qwer", "ggg", "v"];
>     test(value);
> }

Gives errors:

> onlineapp.d(26): Error: function onlineapp.test(ref const(string[3]) qazzz) is not callable using argument types (string[3])
> onlineapp.d(26):        cannot pass rvalue argument ["qwer", "ggg", "v"] of type string[3] to parameter ref const(string[3]) qazzz

WTF?

On 05/12/2020 1:54 AM, Andrey wrote:
> Hello,
> 
>> void test(const ref string[3] qazzz) { qazzz.writeln; }
>>
>> void main()
>> {
>>     enum string[3] value = ["qwer", "ggg", "v"];

That is a compile time constant (remove the enum).

>>     test(value);
>> }
> 
> Gives errors:
> 
>> onlineapp.d(26): Error: function onlineapp.test(ref const(string[3]) qazzz) is not callable using argument types (string[3])
>> onlineapp.d(26):        cannot pass rvalue argument ["qwer", "ggg", "v"] of type string[3] to parameter ref const(string[3]) qazzz
> 
> WTF?

The ref. The problem is the ref. You are passing it a constant, not a variable.

Hm, you mean that enum variable is not a real variable?
I thought that to make CT variable you should mark it as enum (in c++ as constexpr).
How to do it here?

On 05/12/2020 2:42 AM, Andrey wrote:
> Hm, you mean that enum variable is not a real variable?

It is not a variable. It is a constant that cannot be changed and does not exist in the executable.

> I thought that to make CT variable you should mark it as enum (in c++ as constexpr).
> How to do it here?

You are already doing it. This is not what you want. You want a variable that will pass by ref. Remove enum.

On Friday, 4 December 2020 at 13:42:45 UTC, Andrey wrote:
> Hm, you mean that enum variable is not a real variable?
> I thought that to make CT variable you should mark it as enum (in c++ as constexpr).
> How to do it here?

The official name for what you're calling an "enum variable" is "manifest constant" [1]. Manifest constants are like named literals: when you use one, it is treated by the compiler as though you had copy-and-pasted its value at that point in the code. So, for example,

    enum string[3] value = ["qwer", "ggg", "v"];
    test(value);

...is equivalent to

    test(cast(string[3]) ["qwer", "ggg", "v"]);

If you want to declare a compile-time constant that's also an lvalue, you can use `static immutable` instead of `enum`:

    static immutable string[3] value = ["qwer", "ggg", "v"];
    test(value);

[1] https://dlang.org/spec/enum.html#manifest_constants

Thank you!

On Friday, 4 December 2020 at 12:54:25 UTC, Andrey wrote:
> Hello,
>
>> void test(const ref string[3] qazzz) { qazzz.writeln; }
>> 
>> void main()
>> {
>>     enum string[3] value = ["qwer", "ggg", "v"];
>>     test(value);
>> }
>
> Gives errors:

It works if you pass `-preview=rvaluerefparam` to the compiler.

But the other suggestions are better IMO.

—Bastiaan.

On Friday, 4 December 2020 at 12:54:25 UTC, Andrey wrote:
> [...]
> WTF?

If you come from a C or C++ background, it's quite reasonable to think of enum stuff like a #define macro. You're using static arrays, but note that array literals allocate in many use cases. It really is like a C/C++ macro. Use n times = allocate n times. You avoid that with a static immutable completely. That said, if you use the value of that enum only at compile-time, there's no need for a static immutable.

Hope that this rule of thumb sheds some more light on how to achieve certain stuff.