Or, how about a reverse white-boarding session? Let the interviewer draw your info on the board while you sit down. Sounds odd, but this allows you to (a) verbalize the problem/solution for someone else to understand and write it down, and (b) gives you the opportunity to see the bigger picture without getting too close to the board (forest, trees, etc).
You'd be surprised at how many people fail that test.
Things we were looking at:
- is the code correct
- can the code be explained clearly
- does the code scale (memory / speed)
- is the code portable (Solaris was still at thing) ?
- how many external resources were used (copy pasting code from the web is a perfectly acceptable solution)
- unicode support ?
- automated tests ?
You want production grade code delivered on the spot? AUTOMATED TESTS?!? I wouldn't want to work for you.
Production grade code is, in a big part, a matter of good habits. There's no reason those habits can't show up during a test. Especially when the test is very easy.
Nowadays with the virtual interviews it can be hard to visualize, describe and explore some problems with virtual drawing tools..