I write this code in one directory:

module time;

struct Time {
    public int hours, minutes, seconds;
    this(int h, int m, int s) {
        hours = h;
        minutes = m;
        seconds = s;
    }
    Time opBinary(string op : "=")(int secos) {
        assert(secos <= 86_400);
        return new Time(secos / 3600, (secos % 3600) / 60, secos % 60);
    }
}

module testfortime;
import time;
import std.stdio;

void main() {
    Time time = 360;
    write(time.hours);
    readln;
}

After execute 'dmd -run ./testfortime.d' i got this:
".\testfortime.d(6): Error: constructor time.Time.this(int h, int m, int s) is not callable using argument types (int)
.\testfortime.d(6): too few arguments, expected 3, got 1"

WTF? Why standart constructor isnt callable? How its possible in a programming language?

On Friday, 2 September 2022 at 18:39:27 UTC, rikki cattermole wrote:

return new Time(secos / 3600, (secos % 3600) / 60, secos % 60);

And shouldn't an opAssign be void anyways? Doubt there's many people writing stuff like auto c = (a = b);, where a is a struct/class.

On Friday, 2 September 2022 at 18:35:22 UTC, Svyat wrote:

module time;

    struct Time {
        public int hours, minutes, seconds;
        this(int h, int m, int s) {
            hours = h;
            minutes = m;
            seconds = s;
        }
        Time opBinary(string op : "=")(int secos) {
            assert(secos <= 86_400);
            return new Time(secos / 3600, (secos % 3600) / 60, secos % 60);
        }
    }

module testfortime;
import time;
import std.stdio;

    void main() {
        Time time = 360;
        write(time.hours);
        readln;
    }

".\testfortime.d(6): Error: constructor `time.Time.this(int h, int m, int s)` is not callable using argument types `(int)`
.\testfortime.d(6):        too few arguments, expected `3`, got `1`"

First of all, the error message is telling you what is wrong: You are calling the constructor with only one argument, while your constructor is declared to take 3.
If you wanted your call to work, you should have declared the constructor as:

this(int h, int m = 0, int s = 0) { /* Magic */ }

But D will by default give you a default constructor that does exactly that. And the constructor will be properly attributed, because in your case, the constructor should actually be this:

this(int h, int m = 0, int s = 0) inout scope @safe pure nothrow @nogc { /* Magic */ }

So if you just remove the constructor, things will work. Note that in D, as soon as you define one constructor, the default one is no longer generated.

Second, your opBinary cannot compile, because Time is a struct, and if you are returning a new Time in opBinary, you should return a Time*. Currently it's working because you are not using it.

Finally, there is a module in druntime for time management, which provides a very nice API: core.time : Duration. It will allow you to do everything you want to do with your code, and more.
For example: import core.time; auto time = 1.hour; writeln(time);