lib/perl5/5.8.8/SelectSaver.pm

   1 package SelectSaver;
   2
   3 our $VERSION = '1.01';
   4
   5 =head1 NAME
   6
   7 SelectSaver - save and restore selected file handle
   8
   9 =head1 SYNOPSIS
  10
  11     use SelectSaver;
  12
  13     {
  14        my $saver = new SelectSaver(FILEHANDLE);
  15        # FILEHANDLE is selected
  16     }
  17     # previous handle is selected
  18
  19     {
  20        my $saver = new SelectSaver;
  21        # new handle may be selected, or not
  22     }
  23     # previous handle is selected
  24
  25 =head1 DESCRIPTION
  26
  27 A C<SelectSaver> object contains a reference to the file handle that
  28 was selected when it was created.  If its C<new> method gets an extra
  29 parameter, then that parameter is selected; otherwise, the selected
  30 file handle remains unchanged.
  31
  32 When a C<SelectSaver> is destroyed, it re-selects the file handle
  33 that was selected when it was created.
  34
  35 =cut
  36
  37 require 5.000;
  38 use Carp;
  39 use Symbol;
  40
  41 sub new {
  42     @_ >= 1 && @_ <= 2 or croak 'usage: new SelectSaver [FILEHANDLE]';
  43     my $fh = select;
  44     my $self = bless \$fh, $_[0];
  45     select qualify($_[1], caller) if @_ > 1;
  46     $self;
  47 }
  48
  49 sub DESTROY {
  50     my $self = $_[0];
  51     select $$self;
  52 }
  53
  54 1;