Greetings,

For argument's sake, let's say you wanted to create a wrapper class for FileHandle, where you store a real FileHandle as a member of the class (OO aggregation instead of inheritance). (More details: Best way to implement ungetstring?).

One approach is to: (1) Have your class provide custom definitions for all the standard FileHandle methods which would simply call the analogous method on the real FileHandle object:

sub read {
  my $self = shift;
  $self->{real_filehandle}->read(@_);
}

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(2) You'd also need to tie the FileHandle so that stuff like eof would work.

Question: Is there something special about CORE::pipe? There's no TIEHANDLE function for it, and somehow it seems to know that I'm not using a "real" FileHandle. That is, this code: 

  my $out = new MyFileHandleWrapper;
  my $in = new MyFileHandleWrapper;

  pipe $out, $in or die;

  # Fork, close $in and read from $out in the parent,
  # print to $in in the child

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Raises warnings about trying to close and print to unopened filehandles. However, if I change MyFileHandleWrapper to FileHandle, it works fine. If I'm careful to provide all the methods of FileHandle, and I tie all the TIEHANDLE functions, shouldn't this work?

Code is here if you want to run "make test" on my distro.

Thanks!

In reply to Is CORE::pipe magical? by coppit

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