I'm just starting with Ruby, but one of the tricky parts of this language is that since it has no way to declare a variable, you can't tell it that you want a variable to be local. When you assign a value to a variable, you will be using a variable from a containing scope, if any such variable exists. And if no such variable exists, then you'll be creating a new one in the local scope. Block parameters also work this way, which is confusing.
I've attempted to create a workaround. My local() method asserts that the named variables do not yet exist, guaranteeing that any uses that follow will create local variables instead of clobbering existing variables. My code is in the extended entry. See the introductory comment for usage information.
I don't have enough Ruby experience yet to know if this is actually something useful, or just a curiosity. Creating this function was an interesting exercise for me, so I haven't looked yet to see if something like this already exists.
Read on for the code...
