Rust

15.5    Solutions

This section provides the code solutions for the practice exercises in Section 15.4. The code is largely self-explanatory; however, we have included comments and additional explanations wherever necessary to enhance understanding.

1. Expanding a macro for generating multiple functions with return expressions

   fn foo() -> i32 {    42}fn bar() -> String {    "hello world".to_owned()}fn main() {    let result1 = foo();    let result2 = bar();}  

2. Expanding a macro for struct creation with custom fields

   macro_rules! make_struct {    ($name:ident {$($field:ident: $ty:ty),*}) => {        struct $name {            $($field: $ty),*        }    };}// Sample usagemake_struct!(MyStruct {    field1: i32,    field2: String});fn main(){}  

3. Implementing a custom vector initialization macro ...