Christopher,
I am not sure I am understanding the error you are describing. Could
you write up a small failing test for me?
Thanks,
- Stevan
On Mar 27, 2008, at 3:09 PM, Christopher Brown wrote:
Paul and Stevan,
Sorry for the late reply. Thanks for both answers. Stevan, I am rely
impressed with the rapidity of which you and the other Moose members
respond. I am also impressed with you presenting a working
prototype of my
problem in as little time and code as you did. It is really a
testament to
Moose's power.
In the end, I went with the solution that Paul offered. That is, *
create_anon_class()->rebless_instance*. And, I have used this
recipe a
half-dozen or times since. It is really powerful technique for
installing
instance methods. I did run into a snag with reblessing
instances. It
seems that I cannot access the meta object after reblessing. I am
not so
sure why I have the following work on the reblessed object:
$self->meta->add_method( 'test', sub { say "Hello World" } );
# $self
is the reblessed self.
Interestingly enough, the method does not produce an error.
As I am discovering with Moose, there is probably a real simple and
elegant
solutions of which has eluded me. As always, your help is greatly
appreciated.
Best,
Chris
On Thu, Mar 20, 2008 at 8:22 AM, Paul Driver <[EMAIL PROTECTED]>
wrote:
Chris,
If you want to add generated methods to the class, it's
__PACKAGE__->meta->add_method(foobar => sub { print "Foo, bar!
\n" }); I
don't think you want to do this in BUILD though - just at class
compile
time. I do this a lot when I have a bunch of similar methods and
don't want
to repeat myself.
If you want to add methods to a particular instance ONLY, the
thing to do
is to create an anonymous subclass and rebless your instance to that
subclass, and add the methods to the subclass.
Some example code - at BUILD time, add a method named $word that
does say
$word for every word passed into the constructor.
---
use feature q(say);
package Speaker;
use Moose;
has words => (
is => 'ro',
isa => 'ArrayRef[Str]',
predicate => 'has_words',
);
# All Speakers know how to say bar
sub bar {
say 'bar';
}
sub BUILD {
my ($self, $args) = @_;
if ($self->has_words) {
my %methods = map {
my $word = $_;
($word => sub { say $word})
} @{$self->words};
$self->meta->create_anon_class(
superclasses => [__PACKAGE__],
methods => \%methods,
)->rebless_instance($self);
}
}
package main;
my $a = Speaker->new;
my $b = Speaker->new(words => [qw(baz qux)]);
$a->bar; # => "Bar"
$b->bar; # => "Bar"
$b->qux; # => "Qux"
say "A" if $a->isa('Speaker'); # => "A"
say "B" if $b->isa('Speaker'); # => "B"
$a->qux; # Can't locate method "qux" via class "Speaker"
----
On Mar 19, 2008, at 4:22 PM, Christopher Brown wrote:
Dave,
Sorry for taking so long to thank you for your reply. Thanks. On
further
t, it was a silly question, using a plain old method is obviously
the
solution.
I do have follow-up questions, though. Suppose I want to
generate those
plain old methods dynamically. Is there a simple, moose way to
do this
in
the BUILD subroutine. On e way to accomplish this is to assign an
anonymous subroutine to a glob. Like this:
package My::App;
use Moose;
has name => ( is => 'rw', isa=>'Str' );
sub BUILD {
**__PACKAGE__::method = sub { print "hello world\n"; } ;*
}
package main;
my $app = My::App->new( { name => 'Moose' } );
$app->method;
But I don't want to do that. I want to do it the Moose way.
I can hear you ask, but why would you want to do that? Well
suppose, I
create an object that wraps a query. If I can iterate over the
record
set I
can replace the data slot with the new record and still named
methods
that
act as accessors to the record. This beats the snot out of
trying to
instanciate a row object for each record.
Thanks in Advance,
Chris
On Wed, Mar 12, 2008 at 2:41 PM, Dave Rolsky <[EMAIL PROTECTED]>
wrote:
On Wed, 12 Mar 2008, Christopher Brown wrote:
Despite the 'lazy' evaluation, it appears as if the attribute
value
is
being
cached instead of being re-evaluated when the accessor is being
called.
Lazy just means "don't generate the attribute from the default sub
until
the _first_ time it is requested". It's still cached.
If you want to return a different value each time then you just
want a
plain old method, not an attribute.
-dave
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