traits

Is it a safe practice to use default methods as a poor's man version of traits in Java 8? Some claim it may make pandas sad if you use them just for the sake of it, because it's cool, but that's not my intention. It is also often reminded that default methods were introduced to support API evolution and backward compatibility, which is true, but this does not make it wrong or twisted to use them as traits per se. I have the following practical use case in mind: public interface Loggable { default Logger logger() { return LoggerFactory.getLogger(this.getClass()); } } Or perhaps, define a

While trying to understand the Any trait better, I saw that it has an impl block for the trait itself . I don't understand the purpose of this construct, or even if it has a specific name. I made a little experiment with both a "normal" trait method and a method defined in the impl block: trait Foo { fn foo_in_trait(&self) { println!("in foo") } } impl dyn Foo { fn foo_in_impl(&self) { println!("in impl") } } impl Foo for u8 {} fn main() { let x = Box::new(42u8) as Box<dyn Foo>; x.foo_in_trait(); x.foo_in_impl(); let y = &42u8 as &dyn Foo; y.foo_in_trait(); y.foo_in_impl(); // May cause an

I was going through the effective scala slides and it mentions on slide 10 to never use val in a trait for abstract members and use def instead. The slide does not mention in detail why using abstract val in a trait is an anti-pattern. I would appreciate it if someone can explain best practice around using val vs def in a trait for abstract methods A def can be implemented by either of a def , a val , a lazy val or an object . So it's the most abstract form of defining a member. Since traits are usually abstract interfaces, saying you want a val is saying how the implementation should do. If

Traits are used to group some functions to be implemented from a struct, but is it possible to access struct fields from within the trait? I could imagine declaring fields inside the trait so that the fields are abstracted as well. I haven't found such a syntax; is there any other solution? Otherwise, it wouldn't be possible to have non-static methods using a trait, would it? I know object oriented programming from C# and I'm playing around with Rust, trying to adapt the OOP functionality I already know from C#. DK. This sounds like you're misunderstanding how traits work. Traits can't have

I'm trying to create a function that returns an instance of the Shader trait. Here is my drastically simplified code: trait Shader {} struct MyShader; impl Shader for MyShader {} struct GraphicsContext; impl GraphicsContext { fn create_shader(&self) -> Shader { let shader = MyShader; shader } } fn main() {} However I receive the following error: error[E0277]: the trait bound `Shader + 'static: std::marker::Sized` is not satisfied --> src/main.rs:10:32 | 10 | fn create_shader(&self) -> Shader { | ^^^^^^ `Shader + 'static` does not have a constant size known at compile-time | = help: the trait