Trait result_ext::ResultExt
source · pub trait ResultExt<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;
}
Expand description
Extension trait providing additional methods for Result
.
Required Methods§
sourcefn contains<U>(&self, x: &U) -> boolwhere
U: PartialEq<T>,
fn contains<U>(&self, x: &U) -> boolwhere
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);
sourcefn contains_err<F>(&self, f: &F) -> boolwhere
F: PartialEq<E>,
fn contains_err<F>(&self, f: &F) -> boolwhere
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);
sourcefn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U
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);
sourcefn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce(E) -> U>(
self,
f: F,
default: D
) -> U
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);