Programmatically tell if a Unicode character takes up more than one character space in a terminal

Question

I discovered that in the Mac OS X Terminal, some Unicode characters take up more than one character space. For example 27FC (long rightwards arrow from bar). It prints two

Answer 1

This is a bug in the OS X terminal.

I wouldn't recommend trying to work around it, because it will break on other systems (e.g. Linux), and it might get fixed eventually on the Mac. It will also confuse anyone that pastes into another applicaton.