I do like this better. Had to make small change to interceptor but
everything else stayed the same
private IBag<Package> _packages;
[Relationship("packages", RelationshipType.Aggregation,
Cardinality.OneOrMore, inverseProperty = "project")]
public virtual IEnumerable<Package> packages
{
get
{
return _packages;
}
}
public virtual bool AddPackage(Package package, out
List<string> brokenRules)
{
brokenRules = new List<string>();
PrePackageAdd(package, brokenRules);
if (brokenRules.Count> 0 ) return false;
_packages.Add(package);
PostPackageAdd(package);
return true;
}
On Dec 19, 8:33 am, Daniel Fernandes <[email protected]>
wrote:
> How long is a piece of string ?
> If your project really needs you to develop such a collection and your
> consumers are aware of what's going on then I think it's fine.
> But as you said it, fully exposing a collection brings risks and it
> might be better to just revert to public AddXXX/RemoveXXX methods.
> I tend now to use IEnumerable because it's by its definition the items
> references are read-only.
>
> On Dec 19, 2:15 pm, epitka <[email protected]> wrote:
>
> > Well, I have developed one that does all of the houskeeping,
> > synchronize, raise events etc., but now looking at it, I am not sure
> > that is the best way, since the API is not really revealing what is
> > happening. I had to do this for the company I work(ed) for as they had
> > a system that had it's own higher level language that allowed direct
> > manipulation of collections. Now for example if you set a value in
> > collection through indexer and there is already item on that index, it
> > would remove item from the collection, synchronize if bi-directions,
> > raise remove events, that insert item and the same index, synch, and
> > raise add. That is a lot of work that happens that one might not be
> > aware of. Only piece that was not in place was vetoing change.
>
> > On Dec 19, 8:04 am, Daniel Fernandes <[email protected]>
> > wrote:
>
> > > Typical pattern is :
>
> > > IEnumerable<Foo> Foos {
> > > get { return _foos; }}
>
> > > bool AddFoo(Foo foo) {
> > > // business rules here and references management (bi-directional
> > > association, orphan children, multiplicity etc..)}
>
> > > bool RemoveFoo(Foo foo) {
> > > // business rules here and references management (bi-directional,
> > > orphan children, multiplicity, etc..)
>
> > > }
>
> > > There must be around some good IList`1 implementations giving you
> > > callbacks for when an object is added/removed as in Linq2Sql (can't
> > > remember the class name).
>
> > > Daniel
>
> > > On Dec 19, 1:06 pm, epitka <[email protected]> wrote:
>
> > > > That is what I was after, as I've seen people providing Add/Remove
> > > > methods and also exposing it as IList. I guess this post nails it down
> > > > why.
>
> > > >http://tomas.oo-systemutvecklare.se/articles/encapsulation.php
>
> > > > On Dec 18, 11:12 pm, "Greg Young" <[email protected]> wrote:
>
> > > > > I don't even expose it as a collection only as an IEnumerable
>
> > > > > Why do you as a client care how I store it internally?
>
> > > > > Cheers,
>
> > > > > Greg
>
> > > > > On Thu, Dec 18, 2008 at 7:49 PM, epitka <[email protected]>
> > > > > wrote:
>
> > > > > > But how do you protect your collection from being changed; exposing
> > > > > > it
> > > > > > as read-only? But that is not intuitive, if client does not know
> > > > > > that
> > > > > > AddPerson is to be used you would get exception.
> > > > > > Why is #2 not viable?
>
> > > > > > On Dec 18, 9:29 pm, "Greg Young" <[email protected]> wrote:
> > > > > >> 1. don't let collection be modified directly but use Add/remove and
> > > > > >> enforce rule there
>
> > > > > >> Have the aggregate root enforce the validation.
>
> > > > > >> Cheers,
>
> > > > > >> Greg
>
> > > > > >> On Thu, Dec 18, 2008 at 7:25 PM, epitka <[email protected]>
> > > > > >> wrote:
>
> > > > > >> > This is probably more a DDD question then NH. Let say you have
> > > > > >> > observable collections that raise events before collection gets
> > > > > >> > changed and after. Let's say you have a rule that only person's
> > > > > >> > over
> > > > > >> > 21 can be added to the collection. How would you handle this
> > > > > >> > rule:
> > > > > >> > 1. don't let collection be modified directly but use Add/remove
> > > > > >> > and
> > > > > >> > enforce rule there
> > > > > >> > 2. create delegate that will check rule in OnChanging step and
> > > > > >> > veto
> > > > > >> > change
> > > > > >> > 3. allow person to be added and run validate before persisting
> > > > > >> > entity
> > > > > >> > using NH events, basically allow entity to get into invalid state
> > > > > >> > 4. manually invoke validation before commiting changes.
> > > > > >> > 5. something else ?
>
> > > > > >> --
> > > > > >> It is the mark of an educated mind to be able to entertain a
> > > > > >> thought
> > > > > >> without accepting it.
>
> > > > > --
> > > > > It is the mark of an educated mind to be able to entertain a thought
> > > > > without accepting it.
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