Your SlideShare is downloading. ×
Introduction of lambda expression and predicate builder
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Introduction of lambda expression and predicate builder

620

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
620
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
4
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Introduction of Lambda Expression and Predicate Builder Bryan lin 2014/03/07
  • 2. Agenda • Lambda Expression • PredicateBuilder • Implementation of PredicateBuilder
  • 3. Lambda expression • What is a Lambda Expression? • A lambda expression is an anonymous function and it is mostly used to create delegates in LINQ. Simply put, it's a method without a declaration, i.e., access modifier, return value declaration, and name.
  • 4. Lambda expression • Why do we need lambda expressions? (Why would we need to write a method without a name?) • Convenience. It's a shorthand that allows you to write a method in the same place you are going to use it. Especially useful in places where a method is being used only once, and the method definition is short. It saves you the effort of declaring and writing a separate method to the containing class.
  • 5. Lambda expression • Benefits: • Reduced typing. No need to specify the name of the function, its return type, and its access modifier. • When reading the code you don't need to look elsewhere for the method's definition.
  • 6. Lambda expression • Lambda expressions should be short. A complex definition makes the calling code difficult to read.
  • 7. Lambda expression • How do we define a lambda expression? • Lambda basic definition: Parameters => Executed code.
  • 8. PredicateBuilder • Background • Dynamic Predicate Construction • You allow the user to pick, from a check box list, any of the fields that will be included in the query, and to specify the criteria
  • 9. PredicateBuilder
  • 10. PredicateBuilder • Background • Dynamic Predicate Construction • You can do a bunch of switch-ing if logic to figure out what kind of query to render by adding a piece of it at a time • Or you can use lambdas and the PredicateBuilder to inject multiple predicates into an expression tree
  • 11. PredicateBuilder • Using the Code • To combine the two criteria below:
  • 12. PredicateBuilder • Using the Code • Do with the PredcateBuilder:
  • 13. PredicateBuilder • Using the Code • And then:
  • 14. Implementation of PredicateBuilder • Implmentation of and logic:
  • 15. Implementation of PredicateBuilder • Implementation of or logic:
  • 16. References • http://www.codeproject.com/Tips/298963/Understand-Lambda- Expressions-in-3-minutes • http://www.codeproject.com/Articles/28580/LINQ-and-Dynamic- Predicate-Construction-at-Runtime • http://www.albahari.com/nutshell/predicatebuilder.aspx
  • 17. FAQ

×