Making a new object of an undecided class with Moose

[anneli]

See update at EOM.

Hi monks,

I just lately started to OOPify the module I've been working on when I decided I'd go the full hog and Mooseify it.

Before, I was using something like this as a shorthand in the parser to make a node of some type:

sub new_node {
    my ($kind, @args) = @_;
    do {
        no strict 'refs';
        my $class = "Erlang::Parser::Node::$kind";
        &{"${class}::new"}($class, @args)
    }
}

I'm not sure if this is ideal (if not, please do tell!), but it's even less ideal now as I'm getting this with Moose:

Undefined subroutine &Erlang::Parser::Node::Atom::new called at lib/Erlang/Parser/Parser.yp line 33, <DATA> line 1.

If I call new as an actual OO call on the module, it works fine:

my $a = Erlang::Parser::Node::Atom->new(atom => 'xyz'); # sure thing

I'm guessing this is because I don't actually define a new in my own classes (and leave that to Moose), so Erlang::Parser::Node::Whatever::new really doesn't exist!

There is probably some Moose magic I'm missing that I could use to get around this, but I'm still looking! Any wisdom would be very appreciated.

Anneli

Update: ooo... kay. Apparently I missed the most obvious solution of all:

sub new_node {
    my ($kind, %args) = @_;
    "Erlang::Parser::Node::$kind"->new(%args);
}

I have much to learn.

[ikegami]

«Erlang::Parser::Node::Atom» in «Erlang::Parser::Node::Atom->new(atom => 'xyz');» is just a string literal. It can be any expression that produces the string «Erlang::Parser::Node::Atom» (although you might need parens around some expressions because -> binds rather tightly).

my $class = "Erlang::Parser::Node::$type";
$class->new(@args)

or even

"Erlang::Parser::Node::$type"->new(@args)

Altogether:

sub new_node {
   my $kind = shift;
   return "Erlang::Parser::Node::$kind"->new(@_);
}

[anneli]

Thanks! That makes things a lot more clear.

[Anonymous Monk]

Use  my $foo = 'Any::Thing::You::Want'; $foo->new( 1,2,3 );

See Modern Perl: the free book , perlootut.pod

[anneli]

Thank you! I literally (no, literally) just discovered it was this easy!