With it, you can easily pick out the value wrapped in numberless Option<T> and Result<T,Err>.
Furthermore, it won't break down your control flow. You can continue your work even you got a None or Err (All the unexpected value will turn to None)
It means:
fn do_something() {
let value: Option<TypeYourWant> = wrapped_value?.something_return_option()?.something_return_result()?.value;
}would works fine! Just as Kotlin's style.
And you don't need to worry about what Err it would throw!
Usage
#[kotlike]
fn main() {
let a = "Hello".to_string();
let c = File::create("test.txt")?.write_all(a.as_bytes())?.clone();
let mut b: String = String::new();
let len = File::open("test.txt")?.read_to_string(&mut b)?.clone();
println!("Hello, {:?}({:?})!", b,len);
}Expand the macro would look like:
fn main() {
let a = "Hello".to_string();
let c: Option<()> = File::create("test.txt")
.map_or(None, |mut v| {
v.write_all(a.as_bytes())
.map_or(None, |mut v| Some(v.clone()))
});
let mut b: String = String::new();
let len: Option<usize> = File::open("test.txt")
.map_or(None, |mut v|{
v.read_to_string(&mut b)
.map_or(None, |mut v| Some(v.clone()))
});
println!("Hello, {:?}({:?})!", b,len);
}Above example is just showing how it works. Don't focus too much on what stupid code does.
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