Re^2: Filehandle Filter

Hey now, 21 years after this inspired module was added, I just wanted to note a small bug in the Filter subroutine (in package Filter::Handle). It should be:

    sub Filter {
      my $fh = shift;
      tie *{ $fh }, __PACKAGE__, @_;
    }
[download]

Note how the subroutine UnFilter uses the shift correctly. Also, it's a shame that this is no longer on CPAN. But this chunk of module is enough to put into one's "private" library for use. Using a CODE reference, you can duplicate all your STDOUT and STDERR (including any that comes out of perl warnings), like the following:

    select STDERR; $|=1;
    select STDOUT; $|=1;
    use FileHandle;
    my $LOG_FH = new FileHandle($logfile, "w");
    $LOG_FH->autoflush;

    open(DUPOUT, ">&STDOUT") or die "Couldn't dup STDOUT: $!\n";
    open(DUPERR, ">&STDERR") or die "Couldn't dup STDERR: $!\n";

    use Filter::Handle qw/subs/;
    our $FILTER_STDOUT = sub 
    { local $_ = "@_";
      print DUPOUT $_; 
      sprintf "[STDOUT]: %s", "@_"
        if (defined $LOG_FH && $LOG_FH->opened);
    };  
    our $FILTER_STDERR = sub 
    { local $_ = "@_";
      print DUPERR $_; 
      sprintf "[STDERR]: %s", "@_"
        if (defined $LOG_FH && $LOG_FH->opened);
    };  
    
    ## Call Filter to tie the filehandles
    ## Call UnFilter to untie the filehandles (don't care)
    Filter \*STDOUT, $LOG_FH, $FILTER_STDOUT;
    Filter \*STDERR, $LOG_FH, $FILTER_STDERR;
[download]

I like this much better than IO::Tee, because I don't need a custom filehandle to print to to get a logfile of all output. I'm continuing to play around with this and may update this thread more later.

Comment on Re^2: Filehandle Filter Select or Download Code

Replies are listed 'Best First'.

Re^3: Filehandle Filter
by choroba (Cardinal) on Nov 23, 2021 at 17:19 UTC

    use Filter::Handle qw/subs/;
    Filter \*STDOUT, sub { "Foo: @_\n" };
    print "Bar";
    UnFilter \*STDOUT;
[download]

Deep recursion on subroutine "Filter::Handle::PRINT" at .../lib/Filter
+/Handle.pm line 51.
Segmentation fault (core dumped)
[download]

When I replace $_[0] with shift, it fails in all the versions from 5.6.2 to blead:

Not a GLOB reference at .../lib/Filter/Handle.pm line 50.
    (in cleanup) Not a GLOB reference at .../lib/Filter/Handle.pm line
+ 25 during global destruction.
[download]

> it's a shame that this is no longer on CPAN

See Text::OutputFilter.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

[reply]
[d/l]
[select]


Your skill will accomplish what the force of many cannot
	PerlMonks