https://github.com/crumblingstatue/try_opt

[Deprecated] Like try!, but for Option
https://github.com/crumblingstatue/try_opt

Last synced: 3 months ago
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[Deprecated] Like try!, but for Option

• Host: GitHub
• URL: https://github.com/crumblingstatue/try_opt
• Owner: crumblingstatue
• Created: 2015-07-05T13:42:28.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2019-01-22T17:44:18.000Z (almost 6 years ago)
• Last Synced: 2024-10-07T05:09:13.590Z (3 months ago)
• Language: Rust
• Homepage:
• Size: 1.95 KB
• Stars: 5
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Deprecated

Rust now allows the `?` operator to be used on `Option`. The `try_opt!` example further below

can be rewritten as the following:

```Rust

use std::collections::HashMap;

fn map_add_checked(map: &HashMap<&str, i32>, lhs: &str, rhs: &str) -> Option {

    let lhs = map.get(lhs)?;

    let rhs = map.get(rhs)?;

    lhs.checked_add(*rhs)

}

fn main() {

    let mut map = HashMap::new();

    map.insert("foo", 2);

    map.insert("bar", 4);

    map.insert("baz", 12);

    assert_eq!(map_add_checked(&map, "foo", "bar"), Some(6));

    assert_eq!(map_add_checked(&map, "baz", "qux"), None);

}

```

Helper macro for unwrapping `Option` values while returning early with an

error if the value of the expression is `None`. Can only be used in

functions that return `Option` because of the early return of `None` that

it provides.

# Examples

```Rust

#[macro_use]

extern crate try_opt;

use std::collections::HashMap;

fn map_add_checked(map: &HashMap<&str, i32>, lhs: &str, rhs: &str) -> Option {

    let lhs = try_opt!(map.get(lhs));

    let rhs = try_opt!(map.get(rhs));

    lhs.checked_add(*rhs)

}

fn main() {

    let mut map = HashMap::new();

    map.insert("foo", 2);

    map.insert("bar", 4);

    map.insert("baz", 12);

    assert_eq!(map_add_checked(&map, "foo", "bar"), Some(6));

    assert_eq!(map_add_checked(&map, "baz", "qux"), None);

}

```