Trait ResultExt 

pub trait ResultExt<T, E> {
    // Required methods
    fn contains<U>(&self, x: &U) -> bool
       where U: PartialEq<T>;
    fn contains_err<F>(&self, f: &F) -> bool
       where F: PartialEq<E>;
    fn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U;
    fn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce(E) -> U>(
        self,
        f: F,
        default: D,
    ) -> U;
}

Extension trait providing additional methods for Result.

Required Methods

fn contains<U>(&self, x: &U) -> bool

where U: PartialEq<T>,

Returns true if the result is an Ok value containing the given value.

Examples

use result_ext::ResultExt;

let x: Result<u32, &str> = Ok(2);
assert_eq!(x.contains(&2), true);

let x: Result<u32, &str> = Ok(3);
assert_eq!(x.contains(&2), false);

let x: Result<u32, &str> = Err("Some error message");
assert_eq!(x.contains(&2), false);

fn contains_err<F>(&self, f: &F) -> bool

where F: PartialEq<E>,

Returns true if the result is an Err value containing the given value.

Examples

use result_ext::ResultExt;

let x: Result<u32, &str> = Ok(2);
assert_eq!(x.contains_err(&"Some error message"), false);

let x: Result<u32, &str> = Err("Some error message");
assert_eq!(x.contains_err(&"Some error message"), true);

let x: Result<u32, &str> = Err("Some other error message");
assert_eq!(x.contains_err(&"Some error message"), false);

fn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U

Returns the result from applying the function f to the contained value if the result is Ok, or returns provided default value if the result is Err.

The f argument of map_or2 is only evaluated if the result is Ok. The default argument of map_or2 is always evaluated – even if the result is Ok. Use map_or_else2 to avoid evaluating the default argument.

Examples

use result_ext::ResultExt;

let x: Result<_, &str> = Ok("foo");
assert_eq!(x.map_or2(|v| v.len(), 23), 3);

let x: Result<&str, _> = Err("bar");
assert_eq!(x.map_or2(|v| v.len(), 23), 23);

fn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce(E) -> U>( self, f: F, default: D, ) -> U

Returns the result from applying the function f to the contained value if the result is Ok, or returns the result from applying the function default to the contained error if the result is Err.

The f argument of map_or_else2 is only evaluated if the result is Ok. The default argument of map_or_else2 is only evaluated if the result is Err. Use map_or2 to always evaluate the default argument.

Examples

use result_ext::ResultExt;

let k = 23;

let x : Result<_, &str> = Ok("foo");
assert_eq!(x.map_or_else2(|v| v.len(), |e| k * 2), 3);

let x : Result<&str, _> = Err("bar");
assert_eq!(x.map_or_else2(|v| v.len(), |e| k * 2), 46);

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<T, E> ResultExt<T, E> for Result<T, E>

fn contains<U>(&self, x: &U) -> bool

where U: PartialEq<T>,

fn contains_err<F>(&self, f: &F) -> bool

where F: PartialEq<E>,

fn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U

fn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce(E) -> U>( self, f: F, default: D, ) -> U

Implementors