On Mon, Feb 23, 2015 at 10:34 PM, Ben Coman <btc@openinworld.com> wrote:

I haven't played with the relation example yet, but will real soon. Just some initial thoughts...

I like RelationSlot. To me association seems one-way while a relation is two-way.

btw, Is there some reason to not match the syntax of the often cited paper "Flexible Object Layout" ?

I see one advantage is that its easier to read all the slot names vertically aligned.

Object subclass: #SlotExampleMovie

slots: {

#name.

#year.

#director => ToOneRelationSlot opposite: #directedMovies class: #SlotExamplePerson.

#actors => ToManyRelationSlot opposite: #actedInMovies class: #SlotExamplePerson. }

classVariables: { }

category: 'SlotAssociations-Tests-Example'

Also maybe an alternative slot class name so that it reads more like a sentence... "#director related to one #directedMovies in class #SlotExamplePerson"

Object subclass: #SlotExampleMovie

slots: {

#name.

#year.

#director => RelatedToOne inverse: #directedMovies inClass: #SlotExamplePerson.

#actors => RelatedToMany inverse: #actedInMovies inClass: #SlotExamplePerson. }

classVariables: { }

category: 'SlotAssociations-Tests-Example'

Or even...

Object subclass: #SlotExampleMovie

slots: {

#name.

#year.

#director => OneRelatedTo many: #directedMovies inClass: #SlotExamplePerson.

#actors => ManyRelatedTo many: #actedInMovies inClass: #SlotExamplePerson. }

classVariables: { }

category: 'SlotAssociations-Tests-Example'

cheers -ben

On Tue, Feb 24, 2015 at 2:33 AM, Jan van de Sandt <jvdsandt@gmail.com> wrote:

On Mon, Feb 23, 2015 at 9:59 AM, Marcus Denker <marcus.denker@inria.fr> wrote:

> On 21 Feb 2015, at 21:11, Jan van de Sandt <jvdsandt@gmail.com> wrote:
>
> Today I experimented a little with the new Slots feature of Pharo 4.0. As an example I implemented support for associations/relationships.
>

Very nice! Can I add this to Pharo4 as an example?

Sure, cool!

My idea is that at first we add these things as examples, and then later take the examples and distill a library of
generally useful slots.

That sounds like a good approach to get familiar with these kind of new features.

Some things I can do to improve the Example

- Add an option to make one side of the association readonly. In most situations I think it's a good idea to update an association only from one side to keep things simple.

- Whats a better name AssociationSlot or RelationSlot? I'm not sure

- As Stéphane said, isn't there a nicer way to declare the associations?

- Better error handling

Jan.

www.tudorgirba.com

"Every thing has its own flow"