File Coverage

blib/lib/File/Coda.pm

Criterion	Covered	Total	%
statement	6	6	100.0
branch			n/a
condition			n/a
subroutine	2	2	100.0
pod			n/a
total	8	8	100.0

# -*- perl -*-
#
# File::Coda  -  a global destructor that closes stdout, with error-checking
#
# This package is intended to be "use"d very early on.
# It simply sets up actions to be executed at the end of execution.
#
# Why ``Coda''?  Its definition strikes me as particularly apt:
#
# coda, n:
#   A few measures added beyond the natural termination of a composition.
#   --- 1913 Webster

package File::Coda;

use strict;
use warnings;

# Program name of our caller
our $ME = $0;
our $VERSION = '1.94';

# Set $? to this value upon failure to close stdout.
our $Exit_status = 1;

END {
    # Nobody ever checks the status of print()s.  That's okay, because
    # if any do fail, we're usually[*] guaranteed to get an indicator
    # when we close() the file handle.
    # [*] Beware the exception, due to a long-standing bug in Perl,
    # fixed in 5.9.1.  See the report and patch here:
    # http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2004-12/msg00072.html
    #
    # If stdout is already closed, we're done.
    defined fileno STDOUT
      or return;
    # Close stdout now, and if that succeeds, simply return.
    close STDOUT
      and return;

    # Errors closing stdout.  Indicate that, and hope stderr is OK.
    warn $ME . ": closing standard output: $!\n";

    # Don't be so arrogant as to assume that we're the first END handler
    # defined, and thus the last one invoked.  There may be others yet
    # to come.  $? will be passed on to them, and to the final _exit().
    #
    # If it isn't already an error, make it one (and if it _is_ an error,
    # preserve the value: it might be important).
    $? ||= $Exit_status;
}

1;

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