Auto Access to non-Indexed Collections : Or How I Learned to Stop Worrying and Love the VB Compiler

re: Auto Access to non-Indexed Collections : Or How I Learned to Stop Worrying and Love the VB Compiler

Stumbled Upon — Wed, 03 Apr 2013 20:13:19 GMT

Thanks so much for posting this! Was wondering the same.

Beth Massi — Wed, 21 Apr 2010 20:16:50 GMT

Hey Ward,

I disagree ;-), I like what VB is doing here as the syntax follows suit with how array indexers work. So I could swap data sources easily.

I was actually doing some processing in a For i = 0 to count type of loop. I wasn't concerned with the order of the items in the collection at all.

And thanks for (finally) finding some interest in VB ;-)

Cheers,

-B

Ward Bell — Wed, 21 Apr 2010 20:02:34 GMT

I think VB is mistaken in this case and the EF team is correct. The collection has no order guarantee and should not implement indexing.

There is never an entity order guarantee from a query (even OrderBy can take you only so far).

Indexing is misleading and bug-producing. VB is overreaching in this case and I prefer C# asking you to be explicit in your mistake.

Of course both languages support "First" ... and no one can say what that will return.

Btw, why DID you index by 0? Isn't "First" more intentional?

Beth Massi — Sat, 15 Aug 2009 03:12:25 GMT

Thanks Peter,

But the EntityCollection is a Entity Framework type. See my last paragraph on why the EF team chose not to implement the indexer.

Cheers,

-B

Peter Gao — Sat, 15 Aug 2009 03:00:50 GMT

You are right!

your OrderDetails class doesn't actually implement an indexer.

My following code for you information , I implement the indexer:

public string this[int index]

{

get{

if(index>=arrItems.Length)

throw new Exception("The index is over arrItems's length");

else

return arrItems[index];

}

public static void Main()

{

MyIndex myIndex=new MyIndex();

Console.WriteLine(myIndex[2]);

}