std::default::Default
Trait std::default::Default
pub trait Default { fn default() -> Self; }
A trait for giving a type a useful default value.
Sometimes, you want to fall back to some kind of default value, and don't particularly care what it is. This comes up often with struct
s that define a set of options:
struct SomeOptions { foo: i32, bar: f32, }
How can we define some default values? You can use Default
:
#[derive(Default)] struct SomeOptions { foo: i32, bar: f32, } fn main() { let options: SomeOptions = Default::default(); }
Now, you get all of the default values. Rust implements Default
for various primitives types.
If you want to override a particular option, but still retain the other defaults: