use strict;
package Foo;

sub new {
	my $self = {};
	bless $self, 'Foo';
}

sub bar {
	my $self = shift();
	if (@_ == 0) {
		return "Call \$foo->bar()";
	} else {
		return "Call \$foo->bar( '" . join("', '", @_) . "')";
	}
}

package main;

my $foo = new Foo;

use Interpolation 'foo:$@->$' => sub {
	my $cmd = shift();
	no strict 'refs';
	$foo->$cmd(@_);
}; # this creates a tied PACKAGE variable %main::foo !!!

print "x $foo{bar}\n";
print "x $foo{bar}{1}\n";
print "x $foo{bar}{1,2}\n";

# if you want the arrow just create a reference to the %main::foo
my $Foo = \%foo;
print "x $Foo->{bar}\n";
print "x $Foo->{bar}{1}\n";
print "x $Foo->{bar}{1,2}\n";

##</code><code>##

...
package main;

use Interpolation;
my $foo = new Foo;
my $Foo = {};
tie %$Foo, 'Interpolation::general', sub {
	my $cmd = shift();
	no strict 'refs';
	$foo->$cmd(@_);
}, '$@->$';

print "x $Foo->{bar}\n";
print "x $Foo->{bar}{1}\n";
print "x $Foo->{bar}{1,2}\n";

##</code><code>##

...
package main;

use Interpolation;
my $foo = new Foo;

my $CALL = {};
tie %$CALL, 'Interpolation::general', sub {
	my $obj = shift();
	my $cmd = shift();
	no strict 'refs';
	$obj->$cmd(@_);
}, '$$@->$';

print "x $CALL->{$foo}->{bar}\n";
print "x $CALL->{$foo}->{bar}{1}\n";
print "x $CALL->{$foo}->{bar}{1,2}\n";

##</code><code>##

package Foo;
sub baz {
	my $self = shift();
	foreach (@_) {
		print "$_ is a ".(ref $_ ? "reference" : "string")."\n";
	}
}
...
package main;
my $FooX = {};
tie %$FooX, 'Interpolation::general', sub {
	my $cmd = shift();
	no strict 'refs';
	$foo->$cmd(@_);
}, '$$*->$';
print "x $FooX->{baz}{1}{2}{$foo}\n";

or

my $CALLX = {};
tie %$CALLX, 'Interpolation::general', sub {
	my $obj = shift();
#print "Yep it's a ref\n" if ref $obj;
	my $cmd = shift();
	no strict 'refs';
	$obj->$cmd(@_);
}, '$$$*->$';
print "x $CALLX->{$foo}->{baz}{$ref}{100}{$object}\n";