As I pointed out, the reason for doing this is off-topic, let's just say I need a regex that ensures a value is between A and B, where A and B are defined elsewhere (in this case, it's an installer that supports Perl regexes, and I want to check that the port number entered by the user is within an allowable range. Hence the reason I can't post-process the value, I need a regex that does it in one step).

Ideally, I wanted to be able to pass A and B to the regex, in a way similar to defining {min, max} for the number of characters to match.

I want to avoid the breaking down of the min and max values into a sequence of ranges, for exactly the reason you point out.

I still think it is a reasonable question ....