This is a good answer, and there are no problems with it.

Just wanted to point out that it's one of those situations where the /e modifier seems like it's needed, but it's not.

s/([^=]+)=/$changes{$1} . "="/e is effectively the same as s/([^=]+)=/$changes{$1}=/, but the latter is more efficient..

On the other hand, using [^=]+ is a much cleaner and more efficient (and less error prone) solution than .*? which appears once or twice elsewhere in this thread.

-dlc