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Attached to this post is the current version of the C# Collection Templates.

Chris,

Wow, that was fast! Thanks!

Eric J. Smith

Well, I wasn't quite finished yet. :)

I clarified a few comments in the version I just uploaded. If you don't find any problems that should be the version to include in the next CodeSmith release.

Cheers, Chris

Chris,

You know what else I was thinking would be a great addition to these template? I think it would be extremely useful if the template would allow you to specify properties on the collection item to create an indexer for. You would also generate a IndexOf and Contains for each property that you wanted to be able to index by. This would be extremely useful for objects that have an ID or Name or something that you want to look them up by. You would just return the first object that matched the criteria and wouldn't need to worry about multiple items matching.

What do you think?

Eric J. Smith

Eric,

Are you suggesting some kind of dictionary collection whose key is not a separate object but a property of the "value" part of the key/value pair? That sounds interesting but I suspect many pitfalls and a lot of work there... personally I would be leaning towards a standard ArrayList instead, with a simple access method in whatever application class manages that collection.

Chris

Chris,

I've added these to my ArrayList template and the changes are very simple. It's sort of a dictionary, but it's really just a way to access an item in the collection by something other than it's index. A lot of times people store their custom entity objects in a collection and these entity objects have an ID or something that is always going to be unique in the collection. So you simply provide a way of accessing them by this item. One problem I can think of though is that if the property that you want to allow to be indexed on is an int then it couldn't just be an overload of the indexer. So maybe you would have to have something like a GetItemBy<%= PropertyName %> method or something. Or maybe you can think of some better design. But the basic idea is that sometimes you want to be able to locate an item in the collection by something other than it's index.

Thanks,
Eric J. Smith

Chris,

A good example of this is the schema objects that I have added a this[string name] indexer to and a this[owner, name] indexer to. All they do is allow easy access to finding an item in the collection by the name of the schema object so you can do things like:

tableSchema.Columns["MyColumnName"].DataType

Thanks,
Eric J. Smith

Eric,

Chris,

This looks great. This should be very helpful.

As far as the indexer, what I do is just make the this[string name] and this[string owner, string name] indexers read-only. They can only be used to retrieve items and can't be assigned to. If I am unable to find a matching item, I return null. I think what you have works perfect and should solve this need for 99% of the cases.

Thanks,
Eric J. Smith

Eric,

Chris,

Looks good. Perhaps you should add a check to see if they are trying to use "System.Int32", "int", or "Integer" as the KeyType and they have KeyIndexer set to true. If so, then just throw an ApplicationException that says they can't do that.

Also, I didn't see these new methods being defined in the IList interface. Shouldn't they be included there?

Thanks,
Eric J. Smith

Eric,

You mean an ApplicationException in the CodeSmith template code? Sure, that's a good idea, I'll add it to the template.

I don't think any of these methods should be in the interfaces. The purpose of the separate interfaces is to allow one collection of XYZ objects, typed or untyped, regular ArrayList or Keys/Values collection, to be substituted for another. That's only possible if the interfaces are restricted to the standard methods defined by System.Collections.

Cheers, Chris

Chris,

Yeah, throw an ApplicationException in the CodeSmith template and it will be translated to a message box in the GUI.

You're right. They shouldn't be part of the interface. I didn't think of that.

Thanks,
Eric J. Smith

Chris,

Are you getting notifications of new messages from the forums? I'm not getting notifications any more. I need to look into it.

Eric J. Smith