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 for deployment on systems with Perl 5.10 or newer. It 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
unless(open(FH, "< /bogotic") {
    warn "bogo file, dude: $!";
}

# 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 want 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.

Cannot use lexical Fatal with no arguments

You've tried to use use Fatal qw(:lexical) but without supplying a list of which subroutines should adopt the do-or-die behaviour.

:void cannot be used with lexical scope

The :void and :lexical options are mutually exclusive. You can't use them both in the same call to use Fatal.

:lexical must be used as first argument

If you're going to use the :lexical switch, it must be the first option passed to Fatal. If you want to modify some subroutines on a lexical basis, and others on a package-wide basis, simply make two calls to use Fatal.

no Fatal can only start with :lexical

no Fatal only makes sense when disabling Fatal behaviour with lexical scope. If you're going to use it, the first argument must always be :lexical. Eg: no Fatal qw(:lexical open)

GOTCHAS

Subroutines that normally return a list can be Fatalised without clobbering their context. It should be noted that Fatal will consider the subroutine to fail if it returns either an empty list, or a list consisting of a single undef.

BUGS

Fatal only makes changes the package(s) in which it is used, even when changing built-in function. Changing to a new package will cause Fatal not to check calls to any functions for failure (unless Fatal was called there, too).

Fatal clobbers the context in which a function is called, always making it a scalar context, except when the :void tag is used. This problem does not exist in autodie.

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().