[cleanup patch] hoist duplicate code to private method, increase type safety

[neroden]

I'm trying to get the codebase ready for use of typesafe template-style 'min' and 'max'.  This is too big a project to do all at once.  As I've been doing this, I've encountered some sections of code where the code is made much simpler by doing some other code cleanup at the same time, so I'm submitting those as individual patches in advance of the big change.

This is one of those patches.  Compiles and works by itself.