Yan Cui
I help clients go faster for less using serverless technologies.
This article is brought to you by
I never fully recovered my workspace setup when I upgraded my laptop two years ago, and I still miss things today. If only I had known about Gitpod back then…
The other day I had an interesting observation on the optional parameters in C# 4, whereby if you specify a parameter as optional on an interface you don’t actually have to make that parameter optional on any implementing class:
1: public interface MyInterface
2: {
3: void TestMethod(bool flag=false);
4: }
5:
6: public class MyClass : MyInterface
7: {
8: public void TestMethod(bool flag)
9: {
10: Console.WriteLine(flag);
11: }
12: }
Which means you won’t be able to use the implementing class and the interface interchangeably:
1: var obj = new MyClass();
2: obj.TestMethod(); // compiler error
3:
4: var obj2 = new MyClass() as MyInterface;
5: obj2.TestMethod(); // prints false
Naturally, this bags the question of why the compiler doesn’t enforce the implementation to match the default value specified by the contract?
Luckily, my subsequent question on SO was answered by Eric Lippert from the C# compiler team, not to waste time and effort repeating what’s already been said, check out his answer and it’s clear to see the rationale here and why it would be impractical and inconvenient should the compiler does it differently.
References:
Article on positives and pitfalls of using optional parameters
Whenever you’re ready, here are 3 ways I can help you:
- Production-Ready Serverless: Join 20+ AWS Heroes & Community Builders and 1000+ other students in levelling up your serverless game. This is your one-stop shop for quickly levelling up your serverless skills.
- I help clients launch product ideas, improve their development processes and upskill their teams. If you’d like to work together, then let’s get in touch.
- Join my community on Discord, ask questions, and join the discussion on all things AWS and Serverless.