The Language Reference has an example decorator called syslog. It is used to extract the timestamp string from the beginning of each log line.
So, conceptually syslog takes care of the timestamp at the start of the line and other patterns take care of the rest of the line, good for separation of concerns, readability, performance and what not.
Except I found that there is actually no "separation of concern". In the action being decorated, it is still possible to match the timestamp string at the start of the line that was already matched by the syslog decorator. For separation of concern, I would like the patterns inside the decorated action to see the line as starting after whatever was matched by syslog. 'next' does not do this. Is it possible to make the patterns inside the decorated pattern see only the part of the line after whatever was matched by the decorator?
In essence, I would like something like 'next' that presents to the decorated actions a suffix of the original line that starts right after whatever is matched by the decorator.