Created
April 30, 2016 09:03
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// Define a structure named `List` containing a `Vec`. | |
use std::fmt; | |
use std::ops::Deref; | |
struct List(Vec<i32>); | |
impl Deref for List { | |
type Target = Vec<i32>; | |
fn deref(&self) -> &Vec<i32> { | |
&self.0 | |
} | |
} | |
impl fmt::Display for List { | |
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
// Dereference `self` and create a reference to `vec` | |
// via destructuring. | |
let List(ref vec) = *self; | |
try!(write!(f, "[")); | |
// Iterate over `vec` in `v` while enumerating the iteration | |
// count in `count`. | |
for (count, v) in vec.iter().enumerate() { | |
// For every element except the first, add a comma | |
// before calling `write!`. Use `try!` to return on errors. | |
if count != 0 { try!(write!(f, ", ")); } | |
try!(write!(f, "{}", v)); | |
} | |
// Close the opened bracket and return a fmt::Result value | |
write!(f, "]") | |
} | |
} | |
fn main() { | |
let v = List(vec![1, 2, 3]); | |
println!("{:?}", v.len()); | |
} |
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