Re: DIP 57: static foreach

[Andrei Alexandrescu via Digitalmars-d]

On 11/3/15 3:12 PM, Shammah Chancellor wrote:
On Monday, 10 March 2014 at 06:40:49 UTC, Kenji Hara wrote:
2014-03-10 6:31 GMT+09:00 Timon Gehr <timon.g...@gmx.ch>:
http://wiki.dlang.org/DIP57

Thoughts?


From the "Semantics" section:

For static foreach statements, break and continue are supported and
treated like for foreach statements over tuples.

This is questionable sentence. On the foreach with tuple iteration,
break and continue have no effect for the unrolling.

void main()
{
    import std.typetuple, std.stdio;

    foreach (i; TypeTuple!(1, 2, 3))
    {
        static if (i == 2) continue;
        else static if (i == 3) break;

        pragma(msg, "CT: i = ", i); // prints 1, 2, and 3 in CT
        writeln("RT: i = ", i);     // prints only 1 in RT
    }
}

So, I think that static foreach *cannot* support break and continue as
same as foreach with tuples.

Kenji Hara

Ditto.  This needs `static continue` and `static break`.  Without this
functionality, the control flow in `static foreach` becomes very unwieldy.

There's no reason technical or otherwise to require "static" with 
continue/break in static foreach. -- Andrei