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in reply to Closing and re-opening the DATA Filehandle

Ugly hack: 

  my $pos= tell(DATA);
  chomp( my $x= <DATA> );
  warn "Testing($x)";
  {
    my $fh= do { local(*FH); \*FH };
    open $fh, "<&DATA"  or  die "Can't save DATA: $!\n";
    close DATA  or  warn "Can't close DATA: $!\n";
    open DATA, "<&=".fileno($fh)  or  die "Can't restore DATA: $!\n";
    seek DATA, $pos, 0  or  die "Can't reposition DATA: $!\n";
  }
  warn "Testing";
  chomp( $x= <DATA> );
  warn "Testing($x)";
__END__
some data

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produces 
Testing(some data) at redata.pl line 4, <DATA> line 1.
Testing at redata.pl line 12.
Testing(some data) at redata.pl line 14, <DATA> line 1.

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which is what you asked for but needs some serious encapsulation work at least.

        - tye (but my friends call me "Tye")

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Re: (tye)Re: Closing and re-opening the DATA Filehandle
by Adam (Vicar) on Apr 05, 2001 at 01:21 UTC
    Nope. That doesn't work either. I wrapped your code into a sub, so I could call it multiple times and got: 
    Testing(some data) at D:\test.pl line 5, <DATA> line 1.
Testing at D:\test.pl line 13.
Testing(some data) at D:\test.pl line 5, <DATA> line 1.
Can't save DATA: Bad file descriptor

    [download]
    Here is test.pl: 
    sub Tye
{    
  my $pos= tell(DATA);
  chomp( my $x= <DATA> );
  warn "Testing($x)";
  {
    my $fh= do { local(*FH); \*FH };
    open $fh, "<&DATA"  or  die "Can't save DATA: $!\n";
    close DATA  or  warn "Can't close DATA: $!\n";
    open DATA, "<&=".fileno($fh)  or  die "Can't restore DATA: $!\n";
    seek DATA, $pos, 0  or  die "Can't reposition DATA: $!\n";
  }
  warn "Testing";
}

Tye();
Tye();
__END__
some data

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[reply]
[d/l]
[select]

      My mistake. I know this doesn't matter since you found a better solution but this bugged me and I found my mistake.

      I was thinking that the "=" in "<&=" was required when using a numeric file descriptor. But the "=" requests an fdopen() instead of a dup(), that is, the new file handle ends up sharing the same file descriptor with the old file handle. So when $fh is closed (triggered when it goes out of scope and gets destroyed), the file descriptor that DATA is using also gets closed out from under it.

      So just drop the "=" and my code works.

              - tye (but my friends call me "Tye")
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