"When dealing with empty strings, I'd rather check length"

I concur; however, for anyone using a version prior to v5.14.0, a few things to note:

• Prior to v5.12.0, the operand needed to be defined to avoid a "Use of uninitialized value" warning.
  [length() doco for v5.10.1]
• v5.12.0 allowed the operand to be undef (see "perl5120delta: Other potentially incompatible changes"). However, there was a bug (see next point).
  [length() doco for v5.12.0]
• v5.14.0 fixed that bug (from last point): "perl5140delta: Syntax/Parsing Bugs".