Perl in a Nutshell, 2nd Edition

Name

filter

Synopsis

filter() 

Performs the main processing for the filter. Used with closure filters; that is, a closure filter handles the lexical variables that are maintained by the closure. The finished source, as processed by filter, will be returned in $_.

filter returns a status, as follows:

< 0

An error has been encountered.

EOF

End-of-file has been reached unexpectedly.

> 0

Everything is OK.