Fatal(3perl) Perl Programmers Reference Guide Fatal(3perl)
NAME
Fatal - Replace functions with equivalents which succeed or die
SYNOPSIS
use Fatal qw(open close);
open(my $fh, "<", $filename); # No need to check errors!
use File::Copy qw(move);
use Fatal qw(move);
move($file1, $file2); # No need to check errors!
sub juggle { . . . }
Fatal->import('juggle');
BEST PRACTICE
Fatal has been obsoleted by the new autodie pragma. Please use autodie
in preference to "Fatal". autodie supports lexical scoping, throws real
exception objects, and provides much nicer error messages.
The use of ":void" with Fatal is discouraged.
DESCRIPTION
"Fatal" provides a way to conveniently replace functions which normally
return a false value when they fail with equivalents which raise
exceptions if they are not successful. This lets you use these
functions without having to test their return values explicitly on each
call. Exceptions can be caught using "eval{}". See perlfunc and
perlvar for details.
The do-or-die equivalents are set up simply by calling Fatal's "import"
routine, passing it the names of the functions to be replaced. You may
wrap both user-defined functions and overridable CORE operators (except
"exec", "system", "print", or any other built-in that cannot be
expressed via prototypes) in this way.
If the symbol ":void" appears in the import list, then functions named
later in that import list raise an exception only when these are called
in void context--that is, when their return values are ignored. For
example
use Fatal qw/:void open close/;
# properly checked, so no exception raised on error
if (not open(my $fh, '<', '/bogotic') {
warn "Can't open /bogotic: $!";
}
# not checked, so error raises an exception
close FH;
The use of ":void" is discouraged, as it can result in exceptions not
being thrown if you accidentally call a method without void context.
Use autodie instead if you need to be able to disable autodying/Fatal
behaviour for a small block of code.
DIAGNOSTICS
Bad subroutine name for Fatal: %s
You've called "Fatal" with an argument that doesn't look like a
subroutine name, nor a switch that this version of Fatal
understands.
%s is not a Perl subroutine
You've asked "Fatal" to try and replace a subroutine which does not
exist, or has not yet been defined.
%s is neither a builtin, nor a Perl subroutine
You've asked "Fatal" to replace a subroutine, but it's not a Perl
built-in, and "Fatal" couldn't find it as a regular subroutine. It
either doesn't exist or has not yet been defined.
Cannot make the non-overridable %s fatal
You've tried to use "Fatal" on a Perl built-in that can't be
overridden, such as "print" or "system", which means that "Fatal"
can't help you, although some other modules might. See the "SEE
ALSO" section of this documentation.
Internal error: %s
You've found a bug in "Fatal". Please report it using the "perlbug"
command.
BUGS
"Fatal" clobbers the context in which a function is called and always
makes it a scalar context, except when the ":void" tag is used. This
problem does not exist in autodie.
"Used only once" warnings can be generated when "autodie" or "Fatal" is
used with package filehandles (eg, "FILE"). It's strongly recommended
you use scalar filehandles instead.
AUTHOR
Original module by Lionel Cons (CERN).
Prototype updates by Ilya Zakharevich <ilya@math.ohio-state.edu>.
autodie support, bugfixes, extended diagnostics, "system" support, and
major overhauling by Paul Fenwick <pjf@perltraining.com.au>
LICENSE
This module is free software, you may distribute it under the same terms
as Perl itself.
SEE ALSO
autodie for a nicer way to use lexical Fatal.
IPC::System::Simple for a similar idea for calls to system() and
backticks.
perl v5.40.1 2026-08-30 Fatal(3perl)
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