Re: Using a tuple as a function parameter

[Paul Backus via Digitalmars-d-learn]

On Friday, 22 November 2024 at 16:36:43 UTC, Andrew wrote:

I'm getting started using D for some small personal projects and one thing I wanted to do was use a helper function for a tuple. I declared the function like this:

string getOrZeroth(Tuple!(string, string, string) tup, int i) pure {

        return tup[i] == "" ? tup[0] : tup[i];
    }

and would like to use it like this:

    auto foo = tuple("a", "", "c");
    writeln(foo.getOrZeroth(1)); // prints a

but when I try it, I'm getting the below error:

Error: variable \`i\` cannot be read at compile time

You can do this with a `switch` statement:

    string getOrZeroth(Tuple!(string, string, string) tup, int i)
    {
        switch (i)
        {
            static foreach (j; 0 .. tup.length)
            {
                case j:
                    return tup[j] == "" ? tup[0] : tup[j];
            }
            default:
                assert(0, "Tuple index out of bounds");
        }
    }