Re: Debug function / macro

[Paul Backus via Digitalmars-d-learn]

On Monday, 3 February 2020 at 22:07:13 UTC, ag wrote:
Does D have a debugging helper function or macro similar to 
this one in Rust? (https://doc.rust-lang.org/std/macro.dbg.html)

If not, how would one implement this / how difficult would it 
be to implement?

Here's one way you could do it:

string debugPrint(string expr, string file = __FILE__, size_t 
line = __LINE__)
{
    import std.format;

    return q{() {
        import std.stdio: writeln;
        debug writeln(`[%2$s:%3$d] %1$s`, " = ", %1$s);
    }();}.format(expr, file, line);
}

void main()
{
    int x = 123;
    int y = 456;
    mixin(debugPrint("x + y"));
}