FileHandle woes: can't use indirect object method invocation? 
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 FileHandle woes: can't use indirect object method invocation?


Not long ago I asked whether anyone had made a way to find out the
name of a file (ie the parameter passed to open) from a FileHandle

(The reasons for wanting this are

 1) methods that get passed open FileHandles need to be able to issue
    warnings about the associated file.
 2) I hate seeing

     $File->close() or die "Couldn't close $FileName:$!\n";

    where $FileName has to be the name that was used to open $File:
    what if it's not handly to have around>


The general response was "write something to do this yourself".

OK - so I tried.  It's appended.  

The problem now seems to be that I can't use indirect object method
invocation for methods who's names clash with perl functions.  This is
unexpectedly obstructive for perl....

I wanted to create my own 'NamedFile' object, and delegate most of the
method calls to FileHandle.  Unfortunately, this causes perl to barf:

  $File = new NamedFile;
  $File->open(">foo") or die "Couldn't write foo:$!\n";

  print $File "Yay\n";   # booo!  

On the line marked "booo!" I get from perl:

   Not a GLOB reference at ./trial line xxx.

Well - of course it's not: I just want NamedFile::print to get invoked!



works just fine, but this is hardly a 'drop in' replacement for
FileHandle operation!

Thanks for any insights... (including observations about why I
shouldn't be worring about this)!


# Since perl won't let us subclass FileHandle, lets use AUTOLOAD to delegate...

package NamedFile;

require 5.003;

use FileHandle;

sub new
  my $type = shift;

  my $self = {};

  $self->{'FileName'} = "";

  bless $self, $type;


sub open
  my $self = shift;

  $self->{'NamedFile'} = $_[0];

  $self->{'FileHandle'} = new FileHandle;


sub name
  return $self->{'NamedFile'};


  # delegate all other calls to the FileHandle package...

  my $self = shift;

  my $call = $AUTOLOAD;

  $call =~ s/.*:://;



Fri, 29 Sep 2000 03:00:00 GMT  
 [ 1 post ] 

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