perl6-eval.p6

use v6;

multi eval($str, :$lang! where 'perl5') {
    $lang;  # workaround for niecza: '$lang is declared but not used'
    my $inp_file = "tmp.p5";
    my $out_file = "tmp.p6";
    my $fh = open($inp_file, :w);
    $fh.print($str);
    $fh.close;
    shell "perl perlito5.pl -Isrc5/lib -Cperl6 $inp_file > $out_file";
    my $p6_str = slurp $out_file;
    # say "[[$p6_str]]";
    $p6_str.eval;
}

my $p5_str = '
    my @x;
    $x[1] = 2+2;
    say "got $x[1]";
';
eval($p5_str, :lang<perl5>);


=begin comments


Note: to run niecza in osx you need:

    $ export LD_LIBRARY_PATH=/opt/local/lib

    Missing LD_LIBRARY_PATH gives the error:
    "Unhandled exception: System.TypeInitializationException"


Note: fixed in rakudo commit e756635b9e:

    If I define multi eval($str, :$lang! where 'perl5')
    then rakudo can't find eval :lang<perl6> anymore
    because eval is declared as an only sub
    
    This is a workaround (by moritz++):
    
        proto eval(|$) {*};
        multi sub eval($str) {
            $str.eval;
        }


Note: Accessing perl6 variables inside eval (explained by moritz++):

        sub f { say OUTER::.keys }; { my $x = 3; f() }
        # $! GLOBALish $=pod EXPORT !UNIT_MARKER $?PACKAGE ::?PACKAGE $_ &f $/
    
        sub f { say CALLER::.keys }; { my $x = 3; f() }
        # call_sig $x $_ $*DISPATCHER
    
    and you might need to walk the CALLER's OUTER
    this one just gives you the immediate caller's scope


=end comments