|Perl Language Reference Manual|
by Larry Wall and others
Paperback (6"x9"), 724 pages
RRP £29.95 ($39.95)
Sales of this book support The Perl Foundation! Get a printed copy>>>
prints warnings about dubious constructs, such as variable names that are mentioned only once and scalar variables that are used before being set, redefined subroutines, references to undefined filehandles or filehandles opened read-only that you are attempting to write on, values used as a number that don't look like numbers, using an array as though it were a scalar, if your subroutines recurse more than 100 deep, and innumerable other things.
This switch really just enables the internal
$^W variable. You
can disable or promote into fatal errors specific warnings using
__WARN__ hooks, as described in 10 and .
See also 25 and "Perl traps for the unwary" (perltrap) in Perl Tutorials. A new, fine-grained warning
facility is also available if you want to manipulate entire classes
of warnings; see "Perl pragma to control optional warnings" (warnings) in the Perl Library Reference Manual (Volume 1) or 24.
|ISBN 9781906966027||Perl Language Reference Manual||See the print edition|