Book Image

.NET 4.0 Generics Beginner's Guide

By : Sudipta Mukherjee
Book Image

.NET 4.0 Generics Beginner's Guide

By: Sudipta Mukherjee

Overview of this book

Generics were added as part of .NET Framework 2.0 in November 2005. Although similar to generics in Java, .NET generics do not apply type erasure but every object has unique representation at run-time. There is no performance hit from runtime casts and boxing conversions, which are normally expensive..NET offers type-safe versions of every classical data structure and some hybrid ones. This book will show you everything you need to start writing type-safe applications using generic data structures available in Generics API. You will also see how you can use several collections for each task you perform. This book is full of practical examples, interesting applications, and comparisons between Generics and more traditional approaches. Finally, each container is bench marked on the basis of performance for a given task, so you know which one to use and when. This book first covers the fundamental concepts such as type safety, Generic Methods, and Generic Containers. As the book progresses, you will learn how to join several generic containers to achieve your goals and query them efficiently using Linq. There are short exercises in every chapter to boost your knowledge. The book also teaches you some best practices, and several patterns that are commonly available in generic code. Some important generic algorithm definitions are present in Power Collection (an API created by Wintellect Inc.) that are missing from .NET framework. This book shows you how to use such algorithms seamlessly with other generic containers. The book also discusses C5 collections. Java Programmers will find themselves at home with this API. This is the closest to JCF. Some very interesting problems are solved using generic containers from .NET framework, C5, and PowerCollection Algorithms ñ a clone of Google Set and Gender Genie for example! The author has also created a website (http://www.consulttoday.com/genguide) for the book where you can find many useful tools, code snippets, and, applications, which are not the part of code-download section

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.NET 4.0 Generics Beginner's Guide
Sudipta Mukherjee
Jan, 2012 | 396 pages
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Table of Contents (20 chapters)
.NET 4.0 Generics
.NET 4.0 Generics
Credits
Credits
Foreword
Foreword
About the Author
About the Author
Acknowledgement
Acknowledgement
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Why Generics?
Why Generics?
An analogy
Setting up the environment
Summary
2
Lists
Lists
Why bother learning about generic lists?
Types of generic lists
Checking whether a sequence is a palindrome or not
Time for action — creating the generic stack as the buffer
Time for action — completing the rest of the method
Designing a generic anagram finder
Time for action — creating the method
Life is full of priorities, let's bring some order there
Time for action — creating the data structure for the prioritized shopping list
Time for action — let's add some gadgets to the list and see them
Time for action — let's strike off the gadgets with top-most priority after we have bought them
Time for action — let's create an appointment list
Live sorting and statistics for online bidding
Time for action — let's create a custom class for live sorting
Why did we have three LinkedList<T> as part of the data structure?
An attempt to answer questions asked by your boss
Time for action — associating products with live sorted bid amounts
Time for action — finding common values across different bidding amount lists
You will win every scrabble game from now on
Time for action — creating the method to find the character histogram of a word
Time for action — checking whether a word can be formed
Time for action — let's see whether it works
Trying to fix an appointment with a doctor?
Time for action — creating a set of dates of the doctors' availability
Time for action — finding out when both doctors shall be present
Revisiting the anagram problem
Time for action — re-creating the anagram finder
Lists under the hood
Summary
3
Dictionaries
Dictionaries
Types of generic associative structures
Creating a tag cloud generator using dictionary
Time for action — creating the word histogram
Creating a bubble wrap popper game
Time for action — creating the game console
Look how easy it was!
How did we decide we need a dictionary and not a list?
Let's build a generic autocomplete service
Time for action — creating a custom dictionary for autocomplete
Time for action — creating a class for autocomplete
The most common pitfall. Don't fall there!
Let's play some piano
Time for action — creating the keys of the piano
How are we recording the key strokes?
Time for action — switching on recording and playing recorded keystrokes
C# Dictionaries can help detect cancer. Let's see how!
Time for action — creating the KNN API
Time for action — getting the patient records
Time for action — creating the helper class to read a delimited file
Time for action — let's see how to use the predictor
Tuples are great for many occasions including games
Time for action — putting it all together
Why have we used Tuples?
How did we figure out whether the game is over or not?
Summary
4
LINQ to Objects
LINQ to Objects
What makes LINQ?
Time for action — creating an Extension method
Time for action — consuming our new Extension method
Putting it all together, LINQ Standard Query Operators
Time for action — getting the LINQPad
Time for action — finding all names with *am*
Time for action — finding all vowels
Time for action — finding all running processes matching a Regex
Time for action — playing with the indexed version of Where()
Time for action — learn how to go about creating a Where() clause
Time for action — let's say "Hello" to your buddies
Time for action — radio "Lucky Caller" announcement
Time for action — flattening a dictionary
Time for action — leaving the first few elements
Time for action — picking conditionally
Time for action — skipping save looping
Time for action — reversing word-by-word
Time for action — checking whether a given string is a palindrome or not
Time for action — sorting names alphabetically
Time for action — sorting 2D points by their co-ordinates
Time for action — sorting a list of fruits
Time for action — indexing an array of strings
Time for action — grouping by length
Time for action — finding common names from two names' lists
Time for action — finding all names from the list, removing duplicates
Time for action — pulling it all together including duplicates
Time for action — finding all names that appear mutually exclusively
Time for action — removing duplicate song IDs from the list
Time for action — making sure it works!
Time for action — making a list out of IEnumerable<T>
Time for action — tagging names
Time for action — one-to-many mapping
Time for action — finding the first element that satisfies a condition
Time for action — getting acquainted with FirstOrDefault()
Time for action — checking whether a sequence is palindromic
Time for action — understanding ElementAt()
Time for action — check out DefaultIfEmpty()
Time for action — generating arithmetic progression ranges
Time for action — running a filter on a range
Time for action — let's go round and round with Repeat()
Time for action — checking whether there is only one item matching this pattern
Time for action — set to default if there is more than one matching elements
Time for action — checking Any()
Time for action — how to check whether all items match a condition
Summary
5
Observable Collections
Observable Collections
Active change/Statistical change
Passive change/Non-statistical change
Data sensitive change
Time for action — creating a simple math question monitor
Time for action — creating the collections to hold questions
Time for action — attaching the event to monitor the collections
Time for action — dealing with the change as it happens
Time for action — dealing with the change as it happens
Time for action — putting it all together
Time for action — creating a Twitter browser
Time for action — creating the interface
Time for action — creating the TweetViewer user control design
Time for action — gluing the TweetViewer control
Time for action — putting everything together
Time for action — dealing with the change in the list of names in the first tab
Time for action — a few things to beware of at the form load
Time for action — things to do when names get added or deleted
Time for action — sharing the load and creating a task for each BackgroundWorker
Time for action — a sample run of the application
Summary
6
Concurrent Collections
Concurrent Collections
Creating and running asynchronous tasks
Simulating a survey (which is, of course, simultaneous by nature)
Time for action — creating the blocks
Devising a data structure for finding the most in-demand item
Time for action — creating the concurrent move-to-front list
Time for action — simulating a bank queue with multiple tellers
Time for action — making our bank queue simulator more useful
Be a smart consumer, don't wait till you have it all
Exploring data structure mapping
Summary
7
Power Collections
Power Collections
Setting up the environment
BinarySearch()
Time for action — finding a name from a list of names
CartesianProduct()
Time for action — generating names of all the 52 playing cards
RandomShuffle()
Time for action — randomly shuffling the deck
NCopiesOf()
Time for action — creating random numbers of any given length
Time for action — creating a custom random number generator
ForEach()
Time for action — creating a few random numbers of given any length
Rotate() and RotateInPlace()
Time for action — rotating a word
Time for action — creating a word guessing game
RandomSubset()
Time for action — picking a set of random elements
Reverse()
Time for action — reversing any collection
EqualCollections()
Time for action — revisiting the palindrome problem
DisjointSets()
Time for action — checking for common stuff
Time for action — finding anagrams the easiest way
Creating an efficient arbitrary floating point representation
Time for action — creating a huge number API
Creating an API for customizable default values
Time for action — creating a default value API
Mapping data structure
Algorithm conversion strategy
Summary
8
C5 Collections
C5 Collections
Setting up the environment
Time for action — cloning Gender Genie!
Time for action — revisiting the anagram problem
Time for action — Google Sets idea prototype
Time for action — finding the most sought-after item
Sorting algorithms
Summary
9
Patterns, Practices, and Performance
Patterns, Practices, and Performance
Generic container patterns
A special Tuple<> pattern
Time for action — refactoring deeply nested if-else blocks
Best practices when using Generics
Selecting a generic collection
Best practices when creating custom generic collections
Performance analysis
How would we do this investigation?
Benchmarking experiment 1
Benchmarking experiment 2
Benchmarking experiment 3
Benchmarking experiment 4
Benchmarking experiment 5
Benchmarking experiment 6
Benchmarking experiment 7
Benchmarking experiment 8
Benchmarking experiment 9
Summary
Performance Cheat Sheet
Performance Cheat Sheet
Parameters to consider
Migration Cheat Sheet
Migration Cheat Sheet
Pop Quiz Answers
Pop Quiz Answers
Chapter 2
Chapter 3
Chapter 4

Benchmarking experiment 5

How much time does it take to delete a single element in a random location in a list-based collection?

Being able to delete at random locations is also a very important functionality sought by developers. Although it doesn't make much sense in IDictionary implementations and is advisable to avoid; it is almost taken for granted for an IList<T> implantation such as List<T>.

In this experiment, we shall try random deletions from List<T>, LinkedList<T>, C5.LinkedList<T>, C5.ArrayList<T>, C5.HashedLinkedList<T>, and C5.HashedArrayList<T> and see which one wins.

The following is the benchmarking code that will work for LinkedList<T> in System.Collections.Generic: 

using System;
using SCG = System.Collections.Generic;
using System.Linq;
using System.Text;
using C5;
namespace PerformanceMap
{
class Program
{
static void Main(string[] args)
{
SCG.Dictionary<int, double> perfMap
= new SCG.Dictionary<int, double...
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