I use Log::Log4perl in a daemon for logging purposes, but that daemon runs other code via system's and qx//'s, so to capture output I redirect their output to a different file.

However, I thought, it would be good to get their STDxxx output into Log4perl too. Looking around it doesn't seem possible, but then I noticed in the 5.8.x open() perldoc you can open an in-memory IO handle on a scalar variable.

Great, I thought, I can tie a scalar to the log4perl warn and info functions and then use open on that scalar to reopen the STDxxx filehandles. Here is the code I have in my tie module:

    my %function_for;
    my %scalar_ref_for;

    sub TIESCALAR {
        my ( $class, $function ) = @_;

        if ( ref $function ne 'CODE' ) {
            croak('Argument to tie must be a code reference');
        }

        my $self = bless \do { my $anon_scalar }, $class;

        $function_for{ ident $self } = $function;
        $scalar_ref_for{ ident $self } = q{};

        return $self;
    }

    sub STORE {
        my ( $self, @args ) = @_;
        $function_for{ ident $self }->(@args);
    }

    sub FETCH {
        my( $self ) = @_;
        return $scalar_ref_for{ ident $self };
    }
[download]

Running some tests it works fine with:

my $tied_variable;
tie $tied_variable,
    'Tie::Scalar::Function' => sub { ok( defined $_[0], "got something
+ -> $_[0]"
 ) };

$tied_variable = "assignment";
[download]

However, using open against it doesn't work at all:

my $tied_variable;
tie $tied_variable,
    'Tie::Scalar::Function' => sub { ok( defined $_[0], "got something
+ -> $_[0]"
 ) };

warn 'here1:',$tied_variable;

open(my $fh, '>', \$tied_variable);
print {$fh} 'this is a test';

warn 'here2:',$tied_variable;
[download]

$tied_variable does get set by the print on the filehandle but STORE is not called via the tie - somehow its being circumvented.

What am I missing here? I am doing something wrong but I cannot see it...

Thanks

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