On Thu, Jan 29, 2009 at 10:59 AM, Sean Allen <s...@monkeysnatchbanana.com> wrote: > I'm playing around with Moose in a real world work scenario and came across > an interesting question... > > I'm working on a series of reports that mostly similar, you have to > > build up limits to a general query. > pull that query > organize the data > pull all the data together for display and some math > > so you need to get things like: > > limits > value X > value Y > > value X and Y depend on limits to be pulled... > > limits is like this: > > has 'limits' => ( is => 'rw', isa => 'Str', builder => 'build_limits' ); > > could X and Y also be done with builders when they depend on limits being > set? > is there a way to order the initialization of attributes? do i have to order > it? is > moose smart enough to order them correctly ( pie in the sky there )?
What you want I think is 'lazy'. Basically lazy will make attribute initialization happen when the attribute is first *called* rather than when the class is created. Most of the time this is "smart enough" to make things happen properly so if you make X, Y and limits "lazy" then when you call X or Y for the first time they'll call limits during their initialization and cause it to get initialized first. This is such a common idiom that there is an option for has() called 'lazy_build' which when set to true (lazy_build => 1) does the equivalent of: has limits => ( ... builder => '_build_limits', lazy => 1, clearer => '_clear_limits', predicate => 'has_limits'); all that wrapped up in: has limits => ( is => 'rw', isa => 'Str', lazy_build => 1); -Chris
