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<h1>Fatal</h1>
<!-- -->
<ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#BEST-PRACTICE">BEST PRACTICE</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#DIAGNOSTICS">DIAGNOSTICS</a><li><a href="#BUGS">BUGS</a><li><a href="#AUTHOR">AUTHOR</a><li><a href="#LICENSE">LICENSE</a><li><a href="#SEE-ALSO">SEE ALSO</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>Fatal - Replace functions with equivalents which succeed or die</p>
<a name="SYNOPSIS"></a><h1>SYNOPSIS</h1>
<pre class="verbatim"><ol><li> use Fatal qw(open close);</li><li></li><li> open(my $fh, "<", $filename); # No need to check errors!</li><li></li><li> use File::Copy qw(move);</li><li> use Fatal qw(move);</li><li></li><li> move($file1, $file2); # No need to check errors!</li><li></li><li> sub juggle { . . . }</li><li> Fatal->import('juggle');</li></ol></pre><a name="BEST-PRACTICE"></a><h1>BEST PRACTICE</h1>
<p><b>Fatal has been obsoleted by the new <a href="autodie.html">autodie</a> pragma.</b> Please use
<a href="autodie.html">autodie</a> in preference to <code class="inline"><span class="w">Fatal</span></code>
. <a href="autodie.html">autodie</a> supports lexical scoping,
throws real exception objects, and provides much nicer error messages.</p>
<p>The use of <code class="inline"><span class="j">:</span><span class="w">void</span></code>
with Fatal is discouraged.</p>
<a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p><code class="inline"><span class="w">Fatal</span></code>
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
<code class="inline"><a class="l_k" href="functions/eval.html">eval{}</a></code>. See <a href="perlfunc.html">perlfunc</a> and <a href="perlvar.html">perlvar</a> for details.</p>
<p>The do-or-die equivalents are set up simply by calling Fatal's
<code class="inline"><a class="l_k" href="functions/import.html">import</a></code> routine, passing it the names of the functions to be
replaced. You may wrap both user-defined functions and overridable
CORE operators (except <code class="inline"><a class="l_k" href="functions/exec.html">exec</a></code>, <code class="inline"><a class="l_k" href="functions/system.html">system</a></code>, <code class="inline"><a class="l_k" href="functions/print.html">print</a></code>, or any other
built-in that cannot be expressed via prototypes) in this way.</p>
<p>If the symbol <code class="inline"><span class="j">:</span><span class="w">void</span></code>
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</p>
<pre class="verbatim"><ol><li> use Fatal qw/:void open close/;</li><li></li><li> # properly checked, so no exception raised on error</li><li> if (not open(my $fh, '<', '/bogotic') {</li><li> warn "Can't open /bogotic: $!";</li><li> }</li><li></li><li> # not checked, so error raises an exception</li><li> close FH;</li></ol></pre><p>The use of <code class="inline"><span class="j">:</span><span class="w">void</span></code>
is discouraged, as it can result in exceptions
not being thrown if you <i>accidentally</i> call a method without
void context. Use <a href="autodie.html">autodie</a> instead if you need to be able to
disable autodying/Fatal behaviour for a small block of code.</p>
<a name="DIAGNOSTICS"></a><h1>DIAGNOSTICS</h1>
<ul>
<li><a name="Bad-subroutine-name-for-Fatal%3a-%25s"></a><b>Bad subroutine name for Fatal: %s</b>
<p>You've called <code class="inline"><span class="w">Fatal</span></code>
with an argument that doesn't look like
a subroutine name, nor a switch that this version of Fatal
understands.</p>
</li>
<li><a name="%25s-is-not-a-Perl-subroutine"></a><b>%s is not a Perl subroutine</b>
<p>You've asked <code class="inline"><span class="w">Fatal</span></code>
to try and replace a subroutine which does not
exist, or has not yet been defined.</p>
</li>
<li><a name="%25s-is-neither-a-builtin%2c-nor-a-Perl-subroutine"></a><b>%s is neither a builtin, nor a Perl subroutine</b>
<p>You've asked <code class="inline"><span class="w">Fatal</span></code>
to replace a subroutine, but it's not a Perl
built-in, and <code class="inline"><span class="w">Fatal</span></code>
couldn't find it as a regular subroutine.
It either doesn't exist or has not yet been defined.</p>
</li>
<li><a name="Cannot-make-the-non-overridable-%25s-fatal"></a><b>Cannot make the non-overridable %s fatal</b>
<p>You've tried to use <code class="inline"><span class="w">Fatal</span></code>
on a Perl built-in that can't be
overridden, such as <code class="inline"><a class="l_k" href="functions/print.html">print</a></code> or <code class="inline"><a class="l_k" href="functions/system.html">system</a></code>, which means that
<code class="inline"><span class="w">Fatal</span></code>
can't help you, although some other modules might.
See the <a href="#SEE-ALSO">SEE ALSO</a> section of this documentation.</p>
</li>
<li><a name="Internal-error%3a-%25s"></a><b>Internal error: %s</b>
<p>You've found a bug in <code class="inline"><span class="w">Fatal</span></code>
. Please report it using
the <code class="inline"><span class="w">perlbug</span></code>
command.</p>
</li>
</ul>
<a name="BUGS"></a><h1>BUGS</h1>
<p><code class="inline"><span class="w">Fatal</span></code>
clobbers the context in which a function is called and always
makes it a scalar context, except when the <code class="inline"><span class="j">:</span><span class="w">void</span></code>
tag is used.
This problem does not exist in <a href="autodie.html">autodie</a>.</p>
<p>"Used only once" warnings can be generated when <code class="inline"><span class="w">autodie</span></code>
or <code class="inline"><span class="w">Fatal</span></code>
is used with package filehandles (eg, <code class="inline"><span class="w">FILE</span></code>
). It's strongly recommended
you use scalar filehandles instead.</p>
<a name="AUTHOR"></a><h1>AUTHOR</h1>
<p>Original module by Lionel Cons (CERN).</p>
<p>Prototype updates by Ilya Zakharevich <ilya@math.ohio-state.edu>.</p>
<p><a href="autodie.html">autodie</a> support, bugfixes, extended diagnostics, <code class="inline"><a class="l_k" href="functions/system.html">system</a></code>
support, and major overhauling by Paul Fenwick <pjf@perltraining.com.au></p>
<a name="LICENSE"></a><h1>LICENSE</h1>
<p>This module is free software, you may distribute it under the
same terms as Perl itself.</p>
<a name="SEE-ALSO"></a><h1>SEE ALSO</h1>
<p><a href="autodie.html">autodie</a> for a nicer way to use lexical Fatal.</p>
<p><a href="http://search.cpan.org/perldoc/IPC::System::Simple">IPC::System::Simple</a> for a similar idea for calls to <code class="inline"><a class="l_k" href="functions/system.html">system()</a></code>
and backticks.</p>
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