Net design patterns videos source code
In my previous post about learning Python programming through video lectures I stopped at three lectures on Design Patterns. This time I continue from there. If you don't know what a Design Pattern is, think of it as a simple solution to a specific problem that occurs very frequently in software design. For example, suppose you use a bunch of unrelated pieces of code. It is a nice idea to bring the unrelated pieces of code together in a unified interface. This design pattern is called Facade. There are a bunch of patterns like this one! The three lectures are given by Alex Martelli who works as Über Tech Lead for Google. Python Design Patterns, Part I Alex briefly covers the history and main principles of Design Patterns and quickly moves to discussing Structural and Behavioral DPs in Python. Interesting ideas from the lecture: [03:24] The name Design Patterns was first used by Christopher Alexander, an architect, who abstracted the idea of building buildings as building them using well known patterns which can be applied to the same problem over and over again without ever doing it the same way twice. [05:30] Design Patterns are mostly applied to Object Oriented programming because it's the most widely spread programming paradigm nowadays. [08:36] Design Patterns are not invented, they are discovered. [10:00] Alex says that the original book Design Patterns by the Gang of Four should be read only when you are a master of DPs. [13:10] Three classical categories of DPs are - Creational (deal with object instantiaton Structural (deal with composition of objects) and Behavioral (deal with interaction of objects). [14:05] Program to an interface, not to an implementation. [17:00] Use inheritance only when absolutely necessary, otherwise use hold or wrap principle. [18:30] Never have more than one dot - Law of Demeter. [18:50] Inheritance cannot restrict, use wrapping.
Updated with the explanation of Singleton pattern. Design Pattern FAQ What are design patterns? Can you explain factory pattern? Can you explain abstract factory pattern? Can you explain builder pattern? Can you explain prototype pattern? Can you explain shallow copy and deep copy in prototype patterns? Can you explain singleton pattern? Can you explain command patterns? Introduction Here's a small quick FAQ on design patterns in Q and A format. In this section we will cover factory, abstract factory, builder, prototype, shallow and deep prototype, singleton and command patterns. You can read my other design pattern FAQ sections of the same in the below links :- Part 2 Design Pattern FAQ's - Interpreter pattern, iterator pattern, mediator pattern, memento pattern and observer pattern Part 3 Design Pattern FAQ's - state pattern, strategy pattern, visitor pattern, adapter pattern and fly weight pattern Part 4 Design Pattern FAQ's - bridge pattern, composite pattern, decorator pattern, Façade pattern, chain of responsibility( COR proxy pattern and template pattern What are design patterns? Design patterns are documented tried and tested solutions for recurring problems in a given context. So basically you have a problem context and the proposed solution for the same. Design patterns existed in some or other form right from the inception stage of software development. Let’s say if you want to implement a sorting algorithm the first thing comes to mind is bubble sort. So the problem is sorting and solution is bubble sort. Same holds true for design patterns. Which are the three main categories of design patterns? There are three basic classifications of patterns Creational, Structural, and Behavioral patterns. Creational Patterns • Abstract Factory:- Creates an instance of several families of classes • Builder: - Separates object construction from its.
Download videos to your device Access course practice files Get 12 months for the price of 10 “ In a way, I feel like you are rooting for me. Like you are really invested in my experience, and want me to get as much out of these courses as possible this is the best place to start on your journey to learning new material.”— Nadine H.
Updating. Code Plex Project Hosting for Open Source Software Register Sign In home source code downloads documentation discussions issues people license Are you Sure? X By clicking Delete, all history, comments and attachments for this page will be deleted and cannot be restored. Page Info Change History (all pages) All Project Updates Discussions Issue Tracker Downloads Reviews Source Code Wiki it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior. There are three basic kinds of design patterns: structural creational behavioral Structural patterns generally deal with relationships between entities, making it easier for these entities to work together. Creational patterns provide instantiation mechanisms, making it easier to create objects in a way that suits the situation. Behavioral patterns are used in communications between entities and make it easier and more flexible for these entities to communicate. Why should we use them? Design patterns are, by principle, well-thought out solutions to programming problems. Many programmers have encountered these problems before, and have used these 'solutions' to remedy them. If you encounter these problems, why recreate a solution when you can use an already proven answer? Example Let's imagine that you've been given the responsibility of creating a way to merge two classes which do two different things based on the situation. These two classes are heavily used by the existing system in.
Design patterns are solutions to software design problems you find again and again in real-world application development. Patterns are about reusable designs and interactions of objects. The 23 Gang of Four ( Go F) patterns are generally considered the foundation for all other patterns. They are categorized in three groups: Creational, Structural, and Behavioral (for a complete list see below). To give you a head start, the C source code for each pattern is provided in 2 forms: structural and real-world. Structural code uses type names as defined in the pattern definition and UML diagrams. Real-world code provides real-world programming situations where you may use these patterns. A third form. NET optimized, demonstrates design patterns that fully exploit built-in. NET 4.5 features, such as, generics, attributes, delegates, reflection, and more. These and much more are available in our. NET Design Pattern Framework 4.5. You can see the Singleton page for a. NET 4.5 Optimized example. Creational Patterns Abstract Factory Creates an instance of several families of classes Builder Separates object construction from its representation Factory Method Creates an instance of several derived classes Prototype A fully initialized instance to be copied or cloned Singleton A class of which only a single instance can exist Structural Patterns Adapter Match interfaces of different classes Bridge Separates an object’s interface from its implementation Composite A tree structure of simple and composite objects Decorator Add responsibilities to objects dynamically Facade A single class that represents an entire subsystem Flyweight A fine-grained instance used for efficient sharing Proxy An object representing another object Behavioral Patterns Chain of Resp. A way of passing a request between a chain of objects Command Encapsulate a command request as an.
My two cents for such and old question Some people already mentioned, practice and refactoring. I believe the right order to learn about patterns is this: Learn TDD Learn refactoring Learn patterns Most people ignore 1, many believe they can do 2, and almost everybody goes straight for 3. For me the key to improve my software skills was learning TDD. It might be a long time of painful and slow coding, but writing your tests first certainly makes you think a lot about your code. If a class needs too much boilerplate or breaks easily you start noticing bad smells quite fast The main benefit of TDD is that you lose your fear of refactoring your code and force you to write classes that are highly independent and cohesive. Without a good set of tests, it is just too painful to touch something that is not broken. With safety net you will really adventure into drastic changes to your code. That is the moment when you can really start learning from practice. Now comes the point where you must read books about patterns, and to my opinion, it is a complete waste of time trying too hard. I only understood patterns really well after noticing I did something similar, or I could apply that to existing code. Without the safety tests, or habits of refactoring, I would have waited until a new project. The problem of using patterns in a fresh project is that you do not see how they impact or change a working code. I only understood a software pattern once I refactored my code into one of them, never when I introduced one fresh in my code.