赤い pragma(msg)

rederror.d

enum int a = ensureNonNegative!(+42);   // ok
enum int b = ensureNonNegative!(-42);   // error!

template ensureNonNegative(int i)
{
    static if (i < 0)
        mixin error!("Aiiieeeeeeeeeee! i=", i);
    else
        enum int ensureNonNegative = i;
}


//----------------------------------------------------------------------------//

template error(irritants...)
{
    mixin(function
        {
            string ctex;

            ctex ~= `"\u001B[1;31m", `;
            {
                string idx = "0";

                foreach (i; 0 .. irritants.length)
                {
                    ctex ~= "irritants[" ~ idx ~ "], ";
                    idx  ~= "+1";
                }
            }
            ctex ~= `"\u001B[m"`;

            return "pragma(msg, " ~ ctex ~ ");";
        }());
}