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NAME

       autodie - Replace functions with ones that succeed or die with lexical scope

SYNOPSIS

           use autodie;            # Recommended: implies 'use autodie qw(:default)'

           use autodie qw(:all);   # Recommended more: defaults and system/exec.

           use autodie qw(open close);   # open/close succeed or die

           open(my $fh, "<", $filename); # No need to check!

           {
               no autodie qw(open);          # open failures won't die
               open(my $fh, "<", $filename); # Could fail silently!
               no autodie;                   # disable all autodies
           }

           print "Hello World" or die $!;    # autodie DOESN'T check print!

DESCRIPTION

               bIlujDI' yIchegh()Qo'; yIHegh()!

               It is better to die() than to return() in failure.

                       -- Klingon programming proverb.

       The "autodie" pragma provides a convenient way to replace functions that normally return
       false on failure with equivalents that throw an exception on failure.

       The "autodie" pragma has lexical scope, meaning that functions and subroutines altered
       with "autodie" will only change their behaviour until the end of the enclosing block,
       file, or "eval".

       If "system" is specified as an argument to "autodie", then it uses IPC::System::Simple to
       do the heavy lifting.  See the description of that module for more information.

EXCEPTIONS

       Exceptions produced by the "autodie" pragma are members of the autodie::exception class.
       The preferred way to work with these exceptions under Perl 5.10 is as follows:

           use feature qw(switch);

           eval {
               use autodie;

               open(my $fh, '<', $some_file);

               my @records = <$fh>;

               # Do things with @records...

               close($fh);

           };

           given ($@) {
               when (undef)   { say "No error";                    }
               when ('open')  { say "Error from open";             }
               when (':io')   { say "Non-open, IO error.";         }
               when (':all')  { say "All other autodie errors."    }
               default        { say "Not an autodie error at all." }
           }

       Under Perl 5.8, the "given/when" structure is not available, so the following structure
       may be used:

           eval {
               use autodie;

               open(my $fh, '<', $some_file);

               my @records = <$fh>;

               # Do things with @records...

               close($fh);
           };

           if ($@ and $@->isa('autodie::exception')) {
               if ($@->matches('open')) { print "Error from open\n";   }
               if ($@->matches(':io' )) { print "Non-open, IO error."; }
           } elsif ($@) {
               # A non-autodie exception.
           }

       See autodie::exception for further information on interrogating exceptions.

CATEGORIES

       Autodie uses a simple set of categories to group together similar built-ins.  Requesting a
       category type (starting with a colon) will enable autodie for all built-ins beneath that
       category.  For example, requesting ":file" will enable autodie for "close", "fcntl",
       "open" and "sysopen".

       The categories are currently:

           :all
               :default
                   :io
                       read
                       seek
                       sysread
                       sysseek
                       syswrite
                       :dbm
                           dbmclose
                           dbmopen
                       :file
                           binmode
                           close
                           chmod
                           chown
                           fcntl
                           flock
                           ioctl
                           open
                           sysopen
                           truncate
                       :filesys
                           chdir
                           closedir
                           opendir
                           link
                           mkdir
                           readlink
                           rename
                           rmdir
                           symlink
                           unlink
                       :ipc
                           kill
                           pipe
                           :msg
                               msgctl
                               msgget
                               msgrcv
                               msgsnd
                           :semaphore
                               semctl
                               semget
                               semop
                           :shm
                               shmctl
                               shmget
                               shmread
                       :socket
                           accept
                           bind
                           connect
                           getsockopt
                           listen
                           recv
                           send
                           setsockopt
                           shutdown
                           socketpair
                   :threads
                       fork
               :system
                   system
                   exec

       Note that while the above category system is presently a strict hierarchy, this should not
       be assumed.

       A plain "use autodie" implies "use autodie qw(:default)".  Note that "system" and "exec"
       are not enabled by default.  "system" requires the optional IPC::System::Simple module to
       be installed, and enabling "system" or "exec" will invalidate their exotic forms.  See
       "BUGS" below for more details.

       The syntax:

           use autodie qw(:1.994);

       allows the ":default" list from a particular version to be used.  This provides the
       convenience of using the default methods, but the surety that no behavioral changes will
       occur if the "autodie" module is upgraded.

       "autodie" can be enabled for all of Perl's built-ins, including "system" and "exec" with:

           use autodie qw(:all);

FUNCTION SPECIFIC NOTES

   print
       The autodie pragma <does not check calls to "print">.

   flock
       It is not considered an error for "flock" to return false if it fails due to an
       "EWOULDBLOCK" (or equivalent) condition.  This means one can still use the common
       convention of testing the return value of "flock" when called with the "LOCK_NB" option:

           use autodie;

           if ( flock($fh, LOCK_EX | LOCK_NB) ) {
               # We have a lock
           }

       Autodying "flock" will generate an exception if "flock" returns false with any other
       error.

   system/exec
       The "system" built-in is considered to have failed in the following circumstances:

       ·   The command does not start.

       ·   The command is killed by a signal.

       ·   The command returns a non-zero exit value (but see below).

       On success, the autodying form of "system" returns the exit value rather than the contents
       of $?.

       Additional allowable exit values can be supplied as an optional first argument to
       autodying "system":

           system( [ 0, 1, 2 ], $cmd, @args);  # 0,1,2 are good exit values

       "autodie" uses the IPC::System::Simple module to change "system".  See its documentation
       for further information.

       Applying "autodie" to "system" or "exec" causes the exotic forms "system { $cmd } @args "
       or "exec { $cmd } @args" to be considered a syntax error until the end of the lexical
       scope.  If you really need to use the exotic form, you can call "CORE::system" or
       "CORE::exec" instead, or use "no autodie qw(system exec)" before calling the exotic form.

GOTCHAS

       Functions called in list context are assumed to have failed if they return an empty list,
       or a list consisting only of a single undef element.

       Some builtins (e.g. "chdir" or "truncate") has a call signature that cannot completely be
       representated with a Perl prototype.  This means that some valid Perl code will be invalid
       under autodie.  As an example:

         chdir(BAREWORD);

       Without autodie (and assuming BAREWORD is an open filehandle/dirhandle) this is a valid
       call to chdir.  But under autodie, "chdir" will behave like it had the prototype ";$" and
       thus BAREWORD will be a syntax error (under "use strict".  Without strict, it will
       interpreted as a filename).

DIAGNOSTICS

       :void cannot be used with lexical scope
           The ":void" option is supported in Fatal, but not "autodie".  To workaround this,
           "autodie" may be explicitly disabled until the end of the current block with "no
           autodie".  To disable autodie for only a single function (eg, open) use "no autodie
           qw(open)".

           "autodie" performs no checking of called context to determine whether to throw an
           exception; the explicitness of error handling with "autodie" is a deliberate feature.

       No user hints defined for %s
           You've insisted on hints for user-subroutines, either by pre-pending a "!" to the
           subroutine name itself, or earlier in the list of arguments to "autodie".  However the
           subroutine in question does not have any hints available.

       See also "DIAGNOSTICS" in Fatal.

BUGS

       "Used only once" warnings can be generated when "autodie" or "Fatal" is used with package
       filehandles (eg, "FILE").  Scalar filehandles are strongly recommended instead.

       When using "autodie" or "Fatal" with user subroutines, the declaration of those
       subroutines must appear before the first use of "Fatal" or "autodie", or have been
       exported from a module.  Attempting to use "Fatal" or "autodie" on other user subroutines
       will result in a compile-time error.

       Due to a bug in Perl, "autodie" may "lose" any format which has the same name as an
       autodying built-in or function.

       "autodie" may not work correctly if used inside a file with a name that looks like a
       string eval, such as eval (3).

   autodie and string eval
       Due to the current implementation of "autodie", unexpected results may be seen when used
       near or with the string version of eval.  None of these bugs exist when using block eval.

       Under Perl 5.8 only, "autodie" does not propagate into string "eval" statements, although
       it can be explicitly enabled inside a string "eval".

       Under Perl 5.10 only, using a string eval when "autodie" is in effect can cause the
       autodie behaviour to leak into the surrounding scope.  This can be worked around by using
       a "no autodie" at the end of the scope to explicitly remove autodie's effects, or by
       avoiding the use of string eval.

       None of these bugs exist when using block eval.  The use of "autodie" with block eval is
       considered good practice.

   REPORTING BUGS
       Please report bugs via the GitHub Issue Tracker at <https://github.com/pjf/autodie/issues>
       or via the CPAN Request Tracker at <https://rt.cpan.org/NoAuth/Bugs.html?Dist=autodie>.

FEEDBACK

       If you find this module useful, please consider rating it on the CPAN Ratings service at
       <http://cpanratings.perl.org/rate?distribution=autodie> .

       The module author loves to hear how "autodie" has made your life better (or worse).
       Feedback can be sent to <pjf@perltraining.com.au>.

AUTHOR

       Copyright 2008-2009, 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

       Fatal, autodie::exception, autodie::hints, IPC::System::Simple

       Perl tips, autodie at <http://perltraining.com.au/tips/2008-08-20.html>

ACKNOWLEDGEMENTS

       Mark Reed and Roland Giersig -- Klingon translators.

       See the AUTHORS file for full credits.  The latest version of this file can be found at
       <https://github.com/pjf/autodie/tree/master/AUTHORS> .