in reply to Using File Reference

I don't see any immediate error in your code, but here's a couple of things to think about. First, check the status of your open. If you failed to open the file, printing to the file will silently fail.

sub setDestFile {
  my($self, $file) = @_;
  local(*F);
  open( F, ">$file") or die "Cannot open $file for writing: $!";
  $fh = \*F;
  $self->{'destfile'} = $fh;
}

[download]

Next, munge your contructor to print a header right away. If the open is successful and you don't print a header (you can add an a die to print, also), then you know where to look for the problem.

Lastly, in &output, print $text somewhere where you can see it (STDOUT or STDERR come to mind) in order to verify that you are actually passing something.

Cheers,
Ovid

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Replies are listed 'Best First'.
Re: (Ovid) Re: Using File Reference
by Anonymous Monk on Apr 05, 2002 at 18:26 UTC
    This is the entire test program I am using: 
    #!/usr/bin/perl

package Test;
use strict;

sub new {
    my $class = shift;
    return bless {'destFile' => \*STDOUT}, $class;
}

sub open {
    my($self, $file) = @_;
    local(*F);
    open(F, ">$file") or die "cannot open $file for writing: $!";
    $self->{destFile} = \*F;
}

sub output {
    my($self, $text) = @_;
   my $fh = $self->{destFile};
    print "$text\n";
   printf {$self->{destFile}} "$text\n";
}

sub close {
    my $self = shift;
    close( $self->{destFile});
}

package main;

    $a = Test->new;

    $a->open("HELLO");

    $a->output("THIS IS THE LINE TO OUTPUT TO THE FILE");

    $a->close;

    exit;

    [download]
    This program will create the HELLO file in the current directory but it WILL NOT print the output line to it. ?????? IS there anything wrong here.
[reply]
[d/l]
      Add a use warnings pragma to your program and you'll see that the file handle, Test::F, is not open at the time you try to write to it.

      It is closing automatically as it goes out of scope. I think what you want is just a typeglob, not a reference to it. Simply remove the \ from before the typeglob and all is fine. 

      $self->{destFile} = *F;

      [download]
      Cheers,

      - danboo

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