1. C# 4.0 and .NET 4.0
Buu Nguyen, MVP (ASP.NET)
www.buunguyen.net/blog
buunguyen@kms-technology.com
Microsoft Confidential
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2. Agenda
Optional and Named Parameters
Covariance and Contravariance
Dynamic Binding
Threading with Task API
Task Parallel Library (TPL)
PLINQ

3. Optional and Named Parameters

4. ?Quiz
What are 2 issues of this API?

5. Covariance and Contravariance

6. ?Quiz
What is wrong with this code?

7. Covariance Defined
Lets say S is subtype of B and GT is a generic type
GT behaves like subtype of GT on assignment compatibility, i.e.
GT s =
GT b = s;
GT s = (GT)b;
Safe only when GT doesnt expose members receiving T as input (aka input-safe)
Microsoft Confidential
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8. ?Quiz
What is wrong with this code?

9. Contravariance Defined
Lets say S is subtype of B and GT is a generic type
GT behaves like subtype of GT on assignment compatibility, i.e.
GT b =
GT s = b;
GT b = (GT)s;
Safe only when GT doesnt expose members returning T as output (aka output-safe)
Microsoft Confidential
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10. Dynamic Binding

11. ?Quiz
Write a method that prints out the Name property of an anonymous object returned by another method

12. Dynamic binding means
use runtime type for all bindings

13. ?Quiz
A method summing Length properties of all parameters, regardless of actual type

14. ?Quiz
How to builds C# objects that behave like JavaScript objects, i.e. members can be added at any time?

15. ?Quiz
Write a class whose objects can invoke static methods of any particular type
Bonus #1: include non-public static methods
Bonus #2: ignore case

16. ?Quiz
Write a class whose objects can be used as result-caching proxy for the method invocation of any other object

17. Task Parallel Library (TPL) & PLINQ

18. ?Quiz
Write a method calculating Fibonacci number using a thread in thread-pool and returning result to caller

19. Task Parallelism Features
Wait on tasks
Support parent-child relationship
Exception handling
Cancelling tasks
Continuation
Execute one task after another
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20. ?Quiz
Write 3 methods:
Calculate some known Fibonacci numbers
Calculate Fibonacci numbers for a range
Calculate Fibonacci numbers for a list of specified indexes
Each calculation must take place in a thread in thread-pool

21. Parallel Class
Assign delegates to a handful of Task instances, not one-to-one mapping

22. ?Quiz
Write a method which calculate some specified Fibonacci numbers and return the sum of them to the caller