rust / beginner
Snippet
Option: unwrap_or and unwrap_or_else
unwrap_or provides a default value when the Option is None, while unwrap_or_else lazily computes the default only when needed. The latter avoids unnecessary computation and is more efficient when the default is expensive to calculate.
snippet.rs
rust
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fn main() {let numbers = [Some(42), None, Some(100)];for num in numbers.iter() {let value = num.unwrap_or(0);println!("Got: {}", value);}let result: Option<i32> = None;let value = result.unwrap_or_else(|| {println!("Computing default...");99});println!("Value: {}", value);}
Breakdown
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num.unwrap_or(0)
Returns inner value if Some, otherwise returns 0
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unwrap_or_else(|| {
Closure that computes default value lazily
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println!("Computing default...");
Only executes when Option is None
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99
Default value returned when result is None