diff --git a/exercises/traits/traits6.rs b/exercises/traits/traits6.rs new file mode 100644 index 0000000000..d955edea14 --- /dev/null +++ b/exercises/traits/traits6.rs @@ -0,0 +1,76 @@ +// traits6.rs +// +// Your task is to replace the '??' sections so the code compiles. +// Don't change any line other than the marked one. +// Execute `rustlings hint traits6` or use the `hint` watch subcommand for a hint. + +// I AM NOT DONE + +use std::fmt::{self, Debug, Formatter}; + +/// Struct representing a house +#[derive(Default)] +struct House { + area_sqft: u32, + purchase_date: String, +} + +/// Struct representing a vehicle +#[derive(Default)] +struct Vehicle { + name: String, + model: String, + purchase_date: String, +} + +trait Details { + fn summary(&self) -> String; +} + +impl Details for House { + fn summary(&self) -> String { + format!( + "The house has an area of {} sqft and was purchased on {}", + self.area_sqft, self.purchase_date + ) + } +} +impl Details for Vehicle { + fn summary(&self) -> String { + format!( + "The {} vehicle with model {} was purchased on {}", + self.name, self.model, self.purchase_date + ) + } +} + +// TODO: Complete the code +fn foo(flag: bool) -> ?? { + if flag { + Box::new(House { + area_sqft: 5000, + purchase_date: "21 Nov 2017".to_string(), + }) + } else { + Box::new(Vehicle { + name: "BMW".to_string(), + model: "320d".to_string(), + purchase_date: "13 Aug 2022".to_string(), + }) + } +} + +impl Debug for dyn Details { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + // print the summary of the struct returned from the function `foo` + write!(f, "{}", ??) // TODO: Complete the code + } +} + +pub fn main() { + let x = foo(true); + println!("{:?}", x); + // TODO: Complete the code + // print the summary of the struct returned from the function `foo` + println!("{}", ??); +} diff --git a/info.toml b/info.toml index 28f9bb31e7..b9332e7f19 100644 --- a/info.toml +++ b/info.toml @@ -737,6 +737,21 @@ To ensure a parameter implements multiple traits use the '+ syntax'. Try replaci See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#specifying-multiple-trait-bounds-with-the--syntax """ +[[exercises]] +name = "traits6" +path = "exercises/traits/traits6.rs" +mode = "compile" +hint = """ +To ensure a function is able to return incompatible types can be done by using a trait bound that is common to them. +Wrap the shared trait (implemented by the 2 struct types/objects) as a Boxed trait object. Try replacing the '??' with Box<_> +See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits + +Also, in order to make the function printable on console using `:?` symbol. Use the `Debug` trait for the `Details` trait. +Here, the trait object has to implement `Debug` trait, otherwise the function returning trait object will +not be printable on console using {:?} symbol. +See the documentation at: https://doc.rust-lang.org/std/fmt/trait.Debug.html +""" + # QUIZ 3 [[exercises]]