[Advanced Rust] 1.9. Ownership (Quick Recap) - Core Ideas of Ownership, How to Implement Copy Trait, Value Drop, and Drop Order

1.9.1. The Core Idea of Ownership

The core idea of Rust’s memory model is that every value has exactly one owner. In other words, only one place — usually a scope — is responsible for freeing each value.

This behavior is enforced by the borrow checker. If a value is moved — for example by assigning it to a new variable, pushing it into a Vec, placing it on the heap, and so on — then the owner becomes the new location.

The owner is really just a location in memory; the place where the data lives is the value’s owner. A move means the data is transferred from one location to another, and the new location becomes the owner.

However, some types do not follow this rule: if a value’s type implements the Copy trait, then reassignment performs a copy rather than a move. That is, a copy of the value is placed in the new location.