I was just reading about hypothetical variables in Apocalypse 5.

I told a friend why Perl 6 Rules, and he wasn't impressed. It's easy enough to do something like that in C++, and usually we don't bother with anything that elaborate: just assign to temporaries and copy it home to "commit".

So that got me thinking... why limit hypothetical scope to regex?

Have something that works like temp (nee local) that resets the old value only if the block fails, but keeps the current value if the block succeeds.

Also, I don't like something Larry said:

if the variable is not pre-declared, ... the let also serves to declare the variable as lexically scoped to the rest of the regex
Hmm, isn't this going to cause the same surprises as auto-declaring in local (not global) scope that he doesn't like in an earlier installment?

Specifically, declaring a variable in an outer scope that happens to have the same name as my regex-local variable will suddenly change the behavior of the program, with no indication where in the code the meaning changed.

We need, instead, a proper way to declare variables within the regex if that's what's wanted.

—John

In reply to hypothetical variables by John M. Dlugosz

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