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Fatal(3pm)             Perl Programmers Reference Guide             Fatal(3pm)




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(3) for a nicer way to use lexical Fatal.

       IPC::System::Simple(3) for a similar idea for calls to "system()" and
       backticks.



perl v5.24.0                      2016-03-01                        Fatal(3pm)

perl 5.24 - Generated Sun Nov 13 07:44:39 CST 2016
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