[AstralStorm]

A senior developer would also know to not use an enum instead of boolean when not useful and just wasting performance. (because Java and C# make you pay a lot for abstractions you don't use)

What you described is an intermediate programmer trap. A senior programmer would make a design easy to refactor if such a change is needed, but not pay the unnecessary cost up front.

[phamilton]

First, it's hard to come up with useful examples on command. :)

Second, I was thinking more at the data persistence level. Which is harder to change than a simple refactor, and depending on the data store has zero cost (for example in MySQL booleans are just ints). They might then treat it as a boolean on the application side if there are indeed costs there.

Either way, a Senior programmer has that conversation and recognizes the potential costs down the line. Then makes decisions about the tradeoffs.