in reply to Re^3: Moose and default values
in thread Moose and default values

Indeed; it has no ties to Moose. It's simply a function that takes a list and returns a (possibly smaller) list. While it's handy to use it with Moose/Mouse/Moo constructors, it can be used with any functions that take a list of key-value pairs that you want to filter out undefs from.

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

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Re^5: Moose and default values
by morgon (Priest) on Feb 20, 2013 at 22:42 UTC
    It's nice (and only 10 lines of code :-=).

    But say I now wanted not only undefs but everything that is false (e.g. also an empty string) to trigger the default?

    Does Moose not have any mechanics for that?

[reply]

      Maybe something along the lines of:

      around BUILDARGS => sub {
  my $orig   = shift;
  my $self   = shift;
  my $params = $self->$orig(@_);
  $params->{$_} || delete $params->{$_}
    for qw/ foo bar /;
  return $params;
};

      [download]

      This will discard false parameters for the "foo" and "bar" attributes.

      package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
[reply]
[d/l]
        Sure you can always hack togther something, I was more looking for a way to do such things declaratively...

        But your Haskell-ripoff is a at least a step forward - thanks.

[reply]

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