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Making a new object of an undecided class with Moose

by anneli (Pilgrim)
on Oct 22, 2011 at 07:12 UTC ( #933038=perlquestion: print w/replies, xml ) Need Help??

anneli has asked for the wisdom of the Perl Monks concerning the following question:

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.


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.

Replies are listed 'Best First'.
Re: Making a new object of an undecided class with Moose
by ikegami (Patriarch) on Oct 22, 2011 at 07:22 UTC

    «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



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

      Thanks! That makes things a lot more clear.

Re: Making a new object of an undecided class with Moose
by Anonymous Monk on Oct 22, 2011 at 07:18 UTC

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

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