Support PURGE BINARY LOGS TO with non-constant parameter in procedure code somehow

Right now PURGE BINARY LOGS TO apparently can only be used in a stored procedure with static filename string as parameter.

I'd like to create a procedure that only keeps the last N binary log files, and purges any extra binlog files beyond that.

For this I'd need to determine the name of the oldest log name I want to keep, and then somehow need to pass this into the PURGE statement.

But:

• PURGE does not accept a simple @ user variable as argument here
• PURGE inside a procedure does not accept a procedure variable containing the file name either
• PURGE is not supported by PREPARE/EXECUTE either

So all three possible ways to pass in a binlog file name from a variable do not work here.

Being able to run PURGE BINARY LOGS TO ...calculated_filename... looks like something that *should* be possible from within a stored procedure somehow, e.g. to perform such purges from within the server using EVENTs, instead of having to fall back to external scripts and cron jobs to do this ...