[Chicago-talk] What does dollar sign followed by a period represent?

[Richard Reina]

A few years ago I hastily wrote some code that I did not comment very well. In it I found:

 $switch = $. if m!^[0-3]?[0-9]/[0-3]?[0-9]/(?:[0-9]{2})?[0-9]{2}$!; # match date

Can anyone tell me what $. means?

Thanks for any help.

Richard