Borrowed Value Does Not Live Long Enough

Rust's Shared and Exclusive Mutability with Borrowed Values

New Function's Scope and Borrowing

When a new function is introduced, it creates a new scope for variables. This means that the memory allocated to variables within that function will be freed once the function returns. However, if a reference to a variable from an outer scope is returned, the compiler may issue an error stating that the "borrowed value does not live long enough."

Borrowed Value Lifetime

The compiler's error message indicates that the lifetime of the borrowed value is shorter than the lifetime of the reference being returned. This occurs when the borrowed value is used beyond the scope of the function where it was created.

Casting Borrowed Values

If the borrowed value has methods that need to be accessed, it can be cast back to a reference to allow the use of those methods.

Expiring Borrowed Values

There are several ways to expire a borrowed value. One method is to assign the borrowed value to another variable.

Further Reading

To gain a deeper understanding of Rust's borrowing rules and lifetimes, consider revisiting the chapters on references, borrowing, and lifetimes in the Rust documentation.