This is an expected behavior because of how case class works. case class automatically extends two traits, namely Product and Serializable. Product trait is extended as case class is an algebraic data type with product type. Serializable trait is extended so that case class can be treated as a pure data – i.e capable of … Read more
I think this trait does what you want. It detects operator() with any kind of signature even if it’s overloaded and also if it’s templatized: template<typename T> struct is_callable { private: typedef char(&yes)[1]; typedef char(&no)[2]; struct Fallback { void operator()(); }; struct Derived : T, Fallback { }; template<typename U, U> struct Check; template<typename> static … Read more
It seems to be a glitch. The Rust-analyzer LSP is able to infer what the type is supposed to be, but for whatever reason the compiler can’t. From what I can tell, this code doesn’t compile on any version of Rust, and cannot be automatically fixed with cargo fix. Interestingly, the compiler does seem to … Read more
Actually, I’ve wanted this quite often before, but just came up with this idea. You can translate trait T(implicit impl: ClassName) { def foo = … // using impl here } to [EDITED: original version didn’t provide access to implicit for other methods] trait T { // no need to ever use it outside T … Read more
While vectors don’t support std::io::Read, slices do. There is some confusion here caused by Rust being able to coerce a Vec into a slice in some situations but not others. In this case, an explicit coercion to a slice is needed because at the stage coercions are applied, the compiler doesn’t know that Vec<u8> doesn’t … Read more
Rust 1.26 and up impl Trait now exists: fn create_shader(&self) -> impl Shader { let shader = MyShader; shader } It does have limitations, such as not being able to be used in a trait method and it cannot be used when the concrete return type is conditional. In those cases, you need to use … Read more
This sounds like you’re misunderstanding how traits work. Traits can’t have fields. If you want to provide access to a field from a trait, you need to define a method in that trait (like, say, get_blah). If you’re asking whether you can access fields of a struct from within that struct’s implementation of a trait, … Read more
As you’ve noted, impl AsRef<User> for User seems a little pointless since you can just do &user. You could do impl AsRef<String> for User or impl AsRef<u8> for User as alternatives to &user.email and &user.age but those examples are probably misuses of the trait. What does it mean to be able to convert a User … Read more