.NET Competency Group

• Started by Stephen
• Relatively new group
• We are always looking for new members, .NET veterans and newcomers

Overview of C#/.NET
Brownbag

February 2016

After today you will know more about the language that powers the following platforms:

and these...

Core .NET Languages

• C# (v6.0 - 2015)
  • General purpose OOP language
  • C/C++-like syntax
• Visual Basic .NET (v14.0 - 2015)
  • General purpose, successor to VB
• F# (v3.1.1 - 2014)
  • Functional language, originated from ML
• All compile down to CIL
  • (Common Intermediate Language)

History of C#/.NET

• Versions
  • ​https://en.wikipedia.org/wiki/C_Sharp_(programming_language)#Versions
• Versions are almost always backwards compatible
• 3 Main .NET breakpoints (CLR versions)
  • .NET Framework 1.0/1.1
  • .NET Framework 3.5 
  • .NET Framework 4
• Paradigms have shifted over the versions of C#​

C# 2.0

• Released in November 2005
• Large paradigm changes from v1.x, including:
  • ​Generics
  • Iterators
  • Delegates
  • Static Classes

C# 3.0

• Released in November 2007
• Key improvements, including:
  • ​Auto Implemented Properties
  • Extension Methods
  • Lambdas
  • Expression Trees

C# 4.0 and C# 5.0

• Released in November 2010 and August 2012
• C# 4.0 introduced dynamic programming constructs:
  • ​Dynamic binding (Dynamic Language Runtime)
  • Named and optional arguments
• C# 5.0 introduced mainly:
  • Async/Await

C# 6.0

• Released in July 2015
• C# 6.0 introduced many improvements:
  • Compiler as a service (Roslyn)
  • Exception filters
  • Await improvements
  • Null safe propagator (objectInstance?.propertyA)​
  • String Interpolation
  • Default values and initialization paradigms

Getting Started

• For Windows, Visual Studio Community 2015
  • https://www.visualstudio.com/en-us/products/visual-studio-community-vs.aspx
• For Mac, Xamarin Studio (MonoDevelop)​
  • http://www.monodevelop.com/download/
• For all platforms, Visual Studio Code
  • https://code.visualstudio.com/

• ​Other useful tools
  • LINQPad, C# Scratchpad
    • http://www.linqpad.net/
  • ILSpy, .NET Assembly Browser/Disassembler
    • http://ilspy.net/

.NET Package Manager

• NuGet
  • https://www.nuget.org/

• An aside, there is a Windows equivalent to Mac's Homebrew called Chocolatey
  • https://chocolatey.org/

Classes/Objects

Overview

• Familiar, object-oriented programming language class structure
• Inherits from object type
• Instantiate instances of classes using constructors with the syntax of new() or new(param1, ...)
• Utilizes classical inheritance
• Does not support multiple inheritance
• More at: https://msdn.microsoft.com/en-us/library/x9afc042.aspx

Classes/Objects

Class vs Struct

• Classes are:
  • Reference types
  • Used for modeling complex behavior
  • Used throughout the framework and in the wild
• Structures are:
  • Value types
  • Used for modeling simple data structures that typically do not change after assignment
  • Used for the numerics and DateTime in the framework

Classes/Objects

Variables

• Store values or logic (lambdas)
• Strongly-typed, but local variable usage of var keyword in a method is allowed through compiler replacement
• Class variables types
  • Static variables
  • Instance variables

Parameters

• Value parameters
• Reference parameters - use with the ref keyword
• Output parameters - use with the out keyword

Classes/Objects

Access Modifiers

• Public
• Protected - containing class or in derived types
• Internal - in current assembly
• Private - containing class only

Some Other Modifiers

• Const - constant (compile-time)
• Readonly - set once per instance (run-time)
• Sealed - can not be inherited from
• Static - member belongs to type itself
• Abstract - class/members to be defined by derived class
• Virtual - allows implementation to be overridden

Classes/Objects

Interfaces

• Contain definitions for a group of related functionalities that a class or struct can implement
• Contract types that can be used in place of concrete types to allow for flexibility and reusable code
• A class can implement multiple interfaces for composition

Classes/Objects

Constructors

• Mainly used types
  • Instance Constructor
  • Private Constructor (commonly for singletons)

• When objects are initialized, the following execute:
  • Base Constructors
  • Derived Constructors
  • Property Initialization

Classes/Objects

Garbage Collection

• .NET handles garbage collection automatically
• Exceptions include:
  • File and I/O interactions
  • Database connections
  • Graphics
  • Network sockets
• These require handling disposal via the IDisposable interface's .Dispose() method
  • Syntactic sugar with using clauses
• More at: https://msdn.microsoft.com/en-us/library/0xy59wtx(v=vs.110).aspx

Generics

Generics

Overview

• Allows generalization of functionality
• Compiler generates code for each of the different type usages of the generalized functionality
  • Using interfaces can allow run-time binding to a specific type
• Most commonly seen with collections in .NET

Generics

Generic Collections

• System.Collections.Generic
  • List<T>
  • Dictionary<T1, T2>
  • HashSet<T>
  • Tuple<T1, T2, ...>
  • etc...

Generics

Custom Generics

• Specify generic type(s) and constraints (if applicable) in method signature
• Use generic types in place of concrete types or interfaces

Methods

Overview

• Types of Methods
  • Static methods exist on type itself
    • Can not make use of instance members (fields or methods)
  • Instance methods exist on the instance of the class
    • Can make use of static methods and fields
  • ​Anonymous functions/lambdas
    • ​Can be defined with delegates & Func/Action types

• "Getters"/"Setters" are implemented with C# Properties
• Extension methods can add functionality to sealed classes

Methods

Method Signature

• Access Modifier
• Inheritance-related Modifier (optional)
• Asynchronous Modifier (optional)
• Return Type or "void"
• Generic Types <T1, T2, etc...> (optional)
• Input Parameters
• Generic Constraints (optional)

Methods

Lambdas

• Anonymous functions that can be used to create delegates or expression tree types
• Heavily used in LINQ due to code conciseness
• Can be implemented within a closure

Methods

Extension Methods

• Special static methods that appear to be on the class
• Extension methods are defined on public static classes
• Signature of an extension method is the following:

  • public static int WordCount(this String str)

• At compiler converts to a call to the static method

Conditionals and Loops

Conditionals Overview

• Pretty standard and similar to Java
  • Conditionals: If/Switch
• Switch
  • Doesn't fall through
  • Can have multiple cases share same branch
• Ternary operator
• Newer versions of .NET have:
  • Null coalesce (e.g. possiblyNullValue ?? fallbackValue)
  • Null safe navigation (e.g. possiblyNullValue?.propA)

Conditionals and Loops

Looping Overview

• Pretty standard and similar to Java
  • Loops: For/Do-while/While
  • For IEnumerables, can use foreach
• break keyword breaks out of a loop
• continue keyword jumps to the next iteration

LINQ

Overview

• Language-Integrated Query
• Heavily used by Entity Framework and other .NET ORMs
• As the name implies it's a querying language for collections that derive from IEnumerable and IQueryable
  • ​IEnumerable generally are in-memory collections
  • IQueryable represent external data collections
• Can use for sorting, filtering, map/reduce actions
• Functional like programming
• Generally deferred executions with both collection types
  • Exceptions: .ToList(), .First(), .Single(), .Take(), etc.
  • These functions force evaluation

LINQ

Overview (con't)

• SQL-like syntax, but usually ends with the SELECT logic
• Two forms
  • Query Comprehension

    • from num in numbers
      where num % 2 == 0
      orderby num
      select num;

  • Fluent Interface
    • collectionToQuery.Where(...).Select(...)

Learning Resources

• Microsoft Developer Network (MSDN) - C# Reference
  • http://tinyurl.com/c-sharp-reference
• MSDN - 101 LINQ Samples in C#
  • http://tinyurl.com/101-linq
• Dot Net Perls
  • http://www.dotnetperls.com/
• Pluralsight
  • 6 months free with Visual Studio Dev Essentials
  • http://www.pluralsight.com/training

Libraries

Popular .NET Libraries by Microsoft

• ASP.NET
  • MVC - http://www.asp.net/mvc
  • Web API - http://www.asp.net/web-api
  • vNext (preview) - http://www.asp.net/vnext
• Entity Framework [ORM]
  • https://www.nuget.org/packages/EntityFramework​
• WPF (Desktop Windows UI framework)
  • http://tinyurl.com/wpf-vs-2015
• Universal Apps
  • http://tinyurl.com/vs-uwpd

Popular 3rd-Party .NET Libraries

• Json.NET [JSON De/Serializer]
  • https://www.nuget.org/packages/Newtonsoft.Json​
• NUnit [Unit Testing]
  • https://www.nuget.org/packages/NUnit/
• AutoMapper [Object-Object mapper]
  • https://www.nuget.org/packages/AutoMapper/
• AutoFac [IoC Container]
  • https://www.nuget.org/packages/Autofac/
• PostSharp [AOP]
  • https://www.nuget.org/packages/PostSharp
• NLog [Logger]
  • https://www.nuget.org/packages/NLog

Conclusion

• .NET and C# are awesome

• Heavily used in mobile/cross-platform development

• Relatively quick to pick up for a Java developer

• New language features are always being added
  • Compiler and core libraries are open source

Thanks!