sub dosomething {print "in dosomething\n" }

sub wrappit {
    no strict 'refs';
    my ($subname) = @_;
    my $oldsub = \&{$subname};
    *{$subname} = sub {
        print "entering $subname\n";
        my @rv = wantarray ? $oldsub->(@_) : scalar $oldsub->(@_);
        print "leaving $subname\n";
        return wantarray ? @rv : $rv[0];
    };
}
wrappit('dosomething');
dosomething(1..5);