How many developers does it take to change a lightbulb? With the State pattern, not very many.
Topics include:
- The State Pattern
- Design Patterns
- WPF
Source code available at: https://github.com/JasperKent/The-State-Pattern
Friday 22 January 2021
IAsyncEnumerable and Yield Return
Getting data from a Web Service? Why wait until it's all arrived before you start processing?
Topics include:
- C#8
- .Net Core
- IAsyncEnumerable<T>
- yield return
- async
- await
Related videos:
Source code available at: https://github.com/JasperKent/IAsyncEnumerable-Yield-Return
Thursday 21 January 2021
Synchronous Yield Return
Ever wanted to leave a function, and then come back in where you left off? In C# yield return does the trick.
Topics include:
- yield return
- IEnumerable<T>
- Collections
- Fibonacci sequence
Related videos:
Collections vs In-Memory Database
Entity Framework Core in-memory databases are great for unit testing, but would we ever use them in production code?
Topics include:
- .NET Core
- Entity Framework Core
- In-Memory Database
- Unit Testing
- TDD
- Mocking
Source code available at: https://github.com/JasperKent/In-Memory-Benchmark
C# Extension Methods and the Interface Segregation Principle
How do you add a method to and interface without altering the interface? In C#, the answer is extension methods.
Topics include:
- C#
- Extension methods
- SOLID code
- The Interface Segregation Principle
- Turtle graphics
- Kebab casing
Related Videos:
Source code available at: https://github.com/JasperKent/Extension-Methods-and-the-ISP
C# Contravariance
Got your head around covariance? Here's contravariance - welcome to opposite land!
Topics include:
- Contravariance
- C#
- Liskov Substitution Principle
- Interfaces
- Delegates
- Sorting
Related videos:
Source code available at: https://github.com/JasperKent/Contravariance
Wednesday 20 January 2021
C# Covariance
Is a bag of apples a kind of bag of fruit? It all comes down to covariance.
Topics include:
- Covariance
- C#
- Liskov Substitution Principle
- IEnumerable<T>
- List<T>
- Inheritance
- Collections
Related videos:
Implementing IEnumerable
The C# foreach loop works on any standard collection, but what do we need to do to make it work on collections we've written for ourselves?
Topics include:
- C#
- foreach
- IEnumerable<T>
- IEnumerator<T>
- LINQ
- Extension methods
Related videos:
Source code available at: https://github.com/JasperKent/Implementing-IEnumerable
Explicit Interface Implementation
'Disambiguation' is a wonderful word - and it's an important concept in software too. Here's how C# explicit interface implementation can disambiguate otherwise indistinguishable methods.
Topics include:
- C#
- Interfaces
- Explicit interface implementation
Source code available at: https://github.com/JasperKent/Explicit-Interface-Implementation
Random Changes
There are big differences between .NET Framework and .NET Core, but a number of small ones too. Here's a random example - which explains a lot about .NET Standard too.
Topics include:
- .NET Core
- .NET Standard
- .NET Framework
- Random numbers
- Rock, Paper, Scissors
Related videos:
Source code available at: https://github.com/JasperKent/Random-Changes
SOLID: The Dependency Inversion Principle
Dependency Inversion doesn't just mean reversing your existing dependencies. It's about making your entire system easier to extend and maintain.
Topics include:
- C#
- SOLID Code
- The Dependency Inversion Principle
- DIP
- Dependency Injection
- Interfaces
- Rock, Paper, Scissors
Related videos:
SOLID: The Interface Segregation Principle
The Single Responsibility and Open-Closed Principles help us to keep our classes under control. But how do can we do the same for interfaces?
Topics include:
- C#
- SOLID Code
- The Interface Segregation Principle
- ISP
- Interfaces
- Task Parallel Library
- Turtle graphics
Related videos:
Source code available at: https://github.com/JasperKent/SOLID-Interface-Segregation-Principle
SOLID: The Liskov Substitution Principle
Inheritance is one of the most fundamental features of Object-Oriented Programming. Why do we get it wrong so often?
Topics include:
- C#
- SOLID Code
- The Liskov Substitution Principle
- LSP
- Inheritance
- Substitutability
- Abstract classes
- Sealed classes
Related videos:
Source code available at: https://github.com/JasperKent/SOLID-Liskov-Substitution-Principle
Wednesday 13 January 2021
SOLID: The Open-Closed Principle
Making classes open to extension but closed to modification can improve productivity and reduce bugs. Here's how it's done.
Topics include:
- C#
- SOLID Code
- The Open-Closed Principle
- OCP
- Strategy Pattern
- Rock, Paper, Scissors
- Interfaces
Source code available at: https://github.com/JasperKent/SOLID-Open-Closed-Principle
SOLID: The Single Responsibility Principle
Why should a class have only one reason to change? A quick look at the first SOLID principle.
Topics include:
- SOLID Code
- SRP
- Single Responsibility Principle
- Rock, Paper, Scissors, Lizard, Spock
Source code available at: https://github.com/JasperKent/SOLID-Single-Responsibility-Principle
C# Events
Most C# developers use events, but do you know how they relate to delegates? Have you ever implemented an event manually? All is explained here.
Topics include:
- C#
- Events
- Delegates
- Lambda expressions
- Auto-implemented events
- Manually-implemented events
- add
- remove
Related videos:
Source code available at: https://github.com/JasperKent/Events
C# Delegates and Lambdas
C# programmers use delegates and lambdas every day. But do we really understand what they are and how the are related?
Topics include:
- C#
- Delegates
- Lambda expressions
- Func
- Action
Related videos:
Source code available at: https://github.com/JasperKent/Delegates-and-Lambdas
C# Null Forgiving Operator
One of the more obscure features of C#8 is the Null Forgiving Operator. Here's how it works, and when it can get you out of a bind.
Topics include:
- C#
- C#8
- .NET Core
- Nullable references
- Null forgiving operator
- null!
Related videos:
Source code available at: https://github.com/JasperKent/NullForgivingOperator
C# Nullable References
The biggest new feature in C#8 is nullable references. Here's a quick look at how they work and why you should use them.
Topics include:
- C#
- C#8
- .NET Core
- Composition
- Association
- Nullable references
- Nullable values
Related videos:
Source code available at: https://github.com/JasperKent/NullableReferences
C# async, await and Task
Just like JavaScript, C# has async and await keywords. Here we explore the similarities and differences between the two languages.
Topics include:
- C#
- async
- await
- Tasks
- Task Parallel Library
- Asynchronous programming
Related videos:
Source code available at: https://github.com/JasperKent/CSharpAsyncAndAwait
EF Core In-Memory DB Best Practices
In-memory databases are great for unit testing, but tread carefully if you want to avoid false positives - and worse, false negatives.
Topics include:
- .NET Core
- Entity Framework Core
- Unit testing
- Test Driven Development
- Mocking
- In-memory databases
Related videos:
Source code available at: https://github.com/JasperKent/InMemoryDatabase-Best-Practices
EF Core In-Memory Database
Writing a mock repository for unit testing can require a large amount of coding that simply duplicates the features of a real database. Nowadays, the Entity Framework Core In-Memory database does the work for you.
Topics include:
- .NET Core
- Entity Framework Core
- Unit testing
- Test Driven Development
- Mocking
- In-memory databases
Source code available at: https://github.com/JasperKent/InMemoryDatabase
Units
Ever called a function passing seconds instead of milliseconds? Or metres instead of feet? Here's a robust way to avoid problems with units.
Topics include:
- C++
- C++ 11/14
- Time
- Units
- Type safety
Source code available at: https://github.com/JasperKent/Units
ASP.NET Core Pipeline Events
The pipeline works very differently in ASP.NET Core from ASP.NET Framework. Here we examine one aspect of the differences.
Topics include:
- C#
- ASP.NET Core
- Middleware
- Authorization
- Authentication
Source code available at: https://github.com/JasperKent/ASP.NET-Core-Pipeline-Events
JavaScript Async and Await
Once you've got to grips with JavaScript promises, you can make your code much more legible using the keywords async and await.
Topics include:
- JavaScript
- async
- await
- Promises
- Ajax
- Web Services
Related videos:
Source code available at: https://github.com/JasperKent/JavaScript-async-and-await
Promises, Promises
Promises are becoming ever more popular in JavaScript, but it's not always obvious what the benefits are. Here a simple caching example explains the essentials.
Topics include:
- JavaScript
- Promises
- Ajax
- Web Services
Related videos:
Source code available at: https://github.com/JasperKent/JavaScript-Promises
Dynamic Overloading
The dynamic keyword allows decisions about object type to be deferred until runtime. One benefit of this is that we can make method overloading decisions at runtime rather than having them locked in by the compiler.
Topics include:
- C#
- dynamic
- Polymorphism
- Overloading
- Strong typing
Source code available at: https://github.com/JasperKent/DynamicOverloading
IEnumerable vs IQueryable
The two interfaces IQueryable and IEnumerable seem almost interchangeable. Here I discuss one of the key differences, and how it can have a serious effect on performance.
Topics include:
- C#
- IQueryable<T>
- IEnumerable<T>
- Extension methods
- Entity Framework
- SQL
- Performance
- Deferred execution
Related videos:
Source code available at: https://github.com/JasperKent/IQueryable-vs-IEnumerable
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Posts (Atom)
The State Pattern
How many developers does it take to change a lightbulb? With the State pattern, not very many. Topics include: The State Pattern Design Pa...
-
I've been vlogging about all things C# and .NET related for a while now, and I thought that where sometimes a picture paints a thousan... -
In-memory databases are great for unit testing, but tread carefully if you want to avoid false positives - and worse, false negatives. Top...
-
The C# foreach loop works on any standard collection, but what do we need to do to make it work on collections we've written for oursel...
