[Glass] Collection for reduced conflicts, allow indexes and #sort: ?

Hi guys. So...at some point in my app, I have a collection in which I store instances of a persistent class. Imagine class Client, so at some point I have a persistent collection of clients. 

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From: "Mariano Martinez Peck" <[hidden email]>
To: [hidden email]
Sent: Thursday, December 5, 2013 8:06:08 AM
Subject: [Glass] Collection for reduced conflicts, allow indexes and #sort: ?

Hi guys. So...at some point in my app, I have a collection in which I store instances of a persistent class. Imagine class Client, so at some point I have a persistent collection of clients. 

Now... I want:

1) Reduced conflict collections

2) Be able to use indexes if I happen to need them later on (as far as I read it needs to be an unordered collection)

correct

3) Be able to sort the collection given a closure

You can use #sorted: (has the advantage of being defined in Grease so it is "common" between GemStone and Pharo) which takes a standard sort block. If you have an indexed collection, you cannot use an arbitrary block to take advantage of the index ... you have to define a query against the collection ...

Just taking into account 1) and 2) it seems the only option is RcIdentityBag. Problem is that I cannot sort such collection with a simple #sort: aBlockClosure. I saw I have #sortWith:, #sortAsending: etc, but that's not what I need. I need to receive a block closure. 

I can send #asSortedCollection: aClosure to the RcIdentityBag but that answers an instance of a SortedCollection, not a RcIdentityBag sorted, which is different. 

 Bags, by definition are not ordered, so to get a sorted result you will end up with some sort of SequenceableCollection as a result, by necessity ...

Dale

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From: "Mariano Martinez Peck" <[hidden email]>
To: "Dale K. Henrichs" <[hidden email]>
Cc: [hidden email]
Sent: Thursday, December 5, 2013 5:46:17 PM
Subject: Re: [Glass] Collection for reduced conflicts, allow indexes and #sort: ?

On Thu, Dec 5, 2013 at 7:36 PM, Dale K. Henrichs <[hidden email]> wrote:

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From: "Mariano Martinez Peck" <[hidden email]>
To: [hidden email]
Sent: Thursday, December 5, 2013 8:06:08 AM
Subject: [Glass] Collection for reduced conflicts, allow indexes and #sort: ?

Hi guys. So...at some point in my app, I have a collection in which I store instances of a persistent class. Imagine class Client, so at some point I have a persistent collection of clients. 

Now... I want:

1) Reduced conflict collections

2) Be able to use indexes if I happen to need them later on (as far as I read it needs to be an unordered collection)

correct

3) Be able to sort the collection given a closure

You can use #sorted: (has the advantage of being defined in Grease so it is "common" between GemStone and Pharo) which takes a standard sort block.

Thanks for the tip. Indeed, using #sorted: is better!

 

If you have an indexed collection, you cannot use an arbitrary block to take advantage of the index ... you have to define a query against the collection ...

Yes, what a pity :( It would be so cool if normal closures received by select: could detect that you have an index there and use it :)

For 3.2 we are providing a new api for the index system to give you more flexibility in forming queries ... basically you create a query string that looks an awful lot like the smalltalk code that you would write for your closure, but instead of compiling into a closure, we compile it into a `formula` that is made up of `predicates` ... we can match `predicates` to specific indexes and arrange to reorder predicates to take advantage of the indexes ... so a query object when `activated` is the moral equivalent of evaluating a select: block with the difference being that we are able to perform the `select:` operation efficiently ...

BTW... (I should test it instead of asking)... indexes are not used automagically neither for sorting? say I do a normal #sorted: over a unordered collection over a field in which I have an index...would that help?  Or I need to explicitly use #sortAscending:  #sortDescending:  #sortWith:  etc in order to take advantage of the index?

You need to use #sortAscending:  #sortDescending:  #sortWith: to take advantage of the index ... that's the way we match up your "query" with the appropriate index

 

Just taking into account 1) and 2) it seems the only option is RcIdentityBag. Problem is that I cannot sort such collection with a simple #sort: aBlockClosure. I saw I have #sortWith:, #sortAsending: etc, but that's not what I need. I need to receive a block closure. 

I can send #asSortedCollection: aClosure to the RcIdentityBag but that answers an instance of a SortedCollection, not a RcIdentityBag sorted, which is different. 

 Bags, by definition are not ordered, so to get a sorted result you will end up with some sort of SequenceableCollection as a result, by necessity ...

Indeed, I know it makes sense :)

I wonder why there isn't any ordered collection that supports RC and indexes. Technically, I can understand the latter (I think) but not that much the former.

Thanks Dale  and Richard for your answers,  

--
Mariano
http://marianopeck.wordpress.com