Wednesday, July 08, 2009

Building Tuple [Matt Ellis]

by BCLTeam via BCL Team Blog on 7/8/2009 4:47:00 AM

For readers who are interested in the work that goes into designing a feature, I wrote an article for MSDN Magazine that appears in this month’s issue.  Check out CLR Inside Out: Building Tuple which introduces the new Tuple type as well as discusses the design work we did behind it.

I’d love to hear feedback on what you think about the article and if you’d like to see more behind the scenes design articles in the future.  I’d also love to answer any questions about the design or why we made the decisions we did.

Also, there is one change we are thinking about making between Beta 1 and Beta 2 around tuple.  In Beta 1 we have a factory method, Tuple.Create, which builds tuples and has some nice type inference properties.  In Beta 1 the overload of this method which takes eight arguments requires that the last element is a tuple and builds an extended tuple.  For example:

Tuple.Create(1, 2, 3, 4, 5, 6, 7, Tuple.Create(8));

Will build an eight element tuple that looks like [1, 2, 3, 4, 5, 6, 7, 8].

Tuple.Create(1, 2, 3, 4, 5, 6, 7, Tuple.Create(8, 9));

Will build a nine element tuple that looks like [1, 2, 3, 4, 5, 6, 7, 8, 9]

For Beta 2 we hope to change this so that eight argument version of Tuple.Create always builds an eight element tuple.  In this case:

Tuple.Create(1, 2, 3, 4, 5, 6, 7, 8);

Will build an eight element tuple that looks like [1, 2, 3, 4, 5, 6, 7, 8]

Tuple.Create(1, 2, 3, 4, 5, 6, 7, Tuple.Create(8));

Will build an eight element tuple that looks like [1, 2, 3, 4, 5, 6, 7, [8]].

Tuple.Create(1, 2, 3, 4, 5, 6, 7, Tuple.Create(8, 9));

Will build an element tuple that looks like [1, 2, 3, 4, 5, 6, 7, [8, 9]]

If you want to build tuples with more than eight elements and your language doesn’t have special tuple syntax, you’ll have to use the Tuple constructors directly.  If we see lots of people doing this we’ll add more overloads to Tuple.Create.

Thanks for reading; I hope everyone enjoys the article and look forward to your questions and comments.  Cheers!