2 releases (1 stable)
1.0.0 | May 2, 2020 |
---|---|
0.1.0 | May 2, 2020 |
#1969 in Rust patterns
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5KB
take-if
A tiny utility for conditionally taking the contents from an Option
. See also Option::take
.
use take_if::TakeIf;
let mut maybe_greeting = Some("Hello, World!");
if let Some(greeting) = maybe_greeting.take_if(|greeting| greeting.starts_with("Hello")) {
println!(r#"Greeting {:?} starts with "Hello""#, greeting);
} else {
println!(r#"There was no greeting, or it didn't start with "Hello""#);
}
Usage
Add take-if to your Cargo.toml
:
[dependencies]
take-if = "1.0.0"
Import the TakeIf
trait in your modules to add the take_if
method to Option
:
use take_if::TakeIf;
let taken = maybe_value.take_if(|value| value.id == 5);
lib.rs
:
Conditionally take a value out of an option.
This crate adds a take_if
extension method to Option
which conditionally
takes the value out of an option, leaving None
in its place if the value was
taken. The predicate function is only called if the option is Some
, and
receives a reference to the option's contents.
If you don't need to take the value conditionally, i.e. you always need to take
the value, use Option::take
instead.
Examples
use take_if::TakeIf;
let mut maybe_greeting = Some("Hello, World!");
if let Some(greeting) = maybe_greeting.take_if(|greeting| greeting.starts_with("Hello")) {
println!(r#"Greeting {:?} starts with "Hello""#, greeting);
} else {
println!(r#"There was no greeting, or it didn't start with "Hello""#);
}