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November 25, 2021 15:23
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[rust] References to traits in structs
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| /// see https://stackoverflow.com/questions/26212397/references-to-traits-in-structs | |
| #![allow(unused)] | |
| use std::borrow::Borrow; | |
| trait Type { | |
| fn type_to_string(&self) -> String; | |
| } | |
| struct BoolType {} | |
| impl Type for BoolType { | |
| fn type_to_string(&self) -> String { | |
| String::from("BOOL") | |
| } | |
| } | |
| struct IntType {} | |
| impl Type for IntType { | |
| fn type_to_string(&self) -> String { | |
| String::from("INT") | |
| } | |
| } | |
| struct TypeInstance { | |
| types: [Box<dyn Type + 'static>; 2], | |
| } | |
| impl TypeInstance { | |
| fn new() -> Self { | |
| Self { | |
| types: [Box::new(BoolType{}), Box::new(IntType{})], | |
| } | |
| } | |
| fn get_bool_instance(&self) -> &dyn Type { | |
| self.types[0].borrow() | |
| } | |
| fn get_int_instance(&self) -> &dyn Type { | |
| self.types[1].borrow() | |
| } | |
| } | |
| fn main() { | |
| let TYPE_INSTANCE: TypeInstance = TypeInstance::new(); | |
| println!("{}", TYPE_INSTANCE.get_bool_instance().type_to_string()); | |
| println!("{}", TYPE_INSTANCE.get_int_instance().type_to_string()); | |
| } |
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