[Boston.pm] interpolate methods in a string

[Alex Aminoff]

I want to interpolate methods in a string as scalars. I wrote some code 
that works, but my questions are
 1) I couldn't find a pre-existing module that does any of this. Can that 
really be true?
 2) I'm not happy with this solution. In particular, what is the scope of 
the tied ${$symbol} ? Will it go out of scope at the end of the call to 
interpolate_methods? If not, then each call to interpolate_methods will 
clutter up namespace and memory with a bunch of little tied scalar 
objects.

package NBER::InterpolateMethods;
use base Exporter;
our @EXPORT = qw(interpolate_methods);

sub interpolate_methods {
    my($object,$template) = @_;

    my $class = ref($object);
    my $namespace = $class . '::';
    foreach my $symbol ( keys %$namespace ) {
        if ( $object->can($symbol) ) {
            tie(${$symbol}, 'NBER::TieMethodScalar', $object, $symbol);
        }
    }

    my $out = eval $template;
    $@ and die "Error parsing template: $@ $!";
    return $out;
}

package NBER::TieMethodScalar;

sub TIESCALAR {
    my ($class,$object,$method) = @_;
    my $self = {object=>$object,
                method=>$method};

    return bless $self, $class;
}

sub FETCH {
    my $self = shift;
    my $method = $self->{method};
    return $self->{object}->$method();
}

sub STORE { die "can not use tied scalar to modify"; };


Thanks for any suggestions,
--
 - Alex Aminoff
   BaseSpace.net

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