c# Quick Study

1. 1) Statically. Write the classes and they get compiled
2. 2) Code generation. T4 templates or databases (code gets generated when you change UI behind the scenes like with WinForms or WPF)
3. 3) Dynamically ie @ RunTime

Factories

it is the most used design pattern in the OOP world because it saves a lot of time in the future when you have to modify one of the classes you used

Factory Method is a class member that acts as a way of creating objects (typically replaces the constructor)

typically a separate class that knows how to construct objects

can implement caching and other storage optimizations; it is natural choice for approaches such as pooling or the Singleton pattern

Differs from the Builder in that with Factory you create the object in one go whereas with Builder it's piecewise construction

Prototype Pattern

Building from an already existing object

Really only 2 ways to implement the Prototype Pattern

• 1) writing code that correctly duplicates your object (performs a deep copy)
• 2) writing code for support of serialization and deserialization (computational penalty)

Deep vs Shallow copying

assigning jane = john doesn't work because any changes to jane object will affect John as well

with value types, the cloning problem does not really exist (cloning a struct just assign to new variable)

strings are immutable, so you can use the assignment operator = on them without worrying that subsequent modifications will affect more objects than it should

Deep Copy

Prototype Factory

Singleton Pattern

One instance of a component in your application(ex. a component that loads a database into memory adn offers a read-only interface)

LazyLoading Singleton

Singleton Issues:

• use in other components it becomes Fimrly Dependent upon our SingletonInstance...
• ...which presents issues with Unit Testing (having to read a live database is frowned upon in Unit Testing)
• SOLUTION = create something seperate that implements the database interface so we can specify where the data is coming from and NOT DEPEND upon that singleton

Singletons and Inversion of Control

• Instead of directly enforcing the lifetime of a class, this funciton is outsourced to an Inversion of Control (IoC) container
• many people believe that using a Singleton in a DI container is the only socially acceptable use of a Singleton...
• ...with this approach if you need to replace a Singleton object with something else, you can do it in one central place: the Container Configuration code

Monostate