- publishing free software manuals
Perl Language Reference Manual
by Larry Wall and others
Paperback (6"x9"), 724 pages
ISBN 9781906966027
RRP £29.95 ($39.95)

Sales of this book support The Perl Foundation! Get a printed copy>>>

25 perldiag: Various Perl diagnostics

These messages are classified as follows (listed in increasing order of desperation):

(W) A warning (optional).
(D) A deprecation (enabled by default).
(S) A severe warning (enabled by default).
(F) A fatal error (trappable).
(P) An internal error you should never see (trappable).
(X) A very fatal error (nontrappable).
(A) An alien error message (not generated by Perl).

The majority of messages from the first three classifications above (W, D & S) can be controlled using the warnings pragma.

If a message can be controlled by the warnings pragma, its warning category is included with the classification letter in the description below.

Optional warnings are enabled by using the warnings pragma or the -w and -W switches. Warnings may be captured by setting $SIG{__WARN__} to a reference to a routine that will be called on each warning instead of printing it. See 10.

Severe warnings are always enabled, unless they are explicitly disabled with the warnings pragma or the -X switch.

Trappable errors may be trapped using the eval operator. See . In almost all cases, warnings may be selectively disabled or promoted to fatal errors using the warnings pragma. See "Perl pragma to control optional warnings" (warnings) in the Perl Library Reference Manual (Volume 1).

The messages are in alphabetical order, without regard to upper or lower-case. Some of these messages are generic. Spots that vary are denoted with a %s or other printf-style escape. These escapes are ignored by the alphabetical order, as are all characters other than letters. To look up your message, just ignore anything that is not a letter.

ISBN 9781906966027Perl Language Reference ManualSee the print edition