Notes (TRPL 04/21): Ownership

4 Ownership

What is Ownership?

Every value in Rust has a variable that’s called its owner.

There can only be one owner at a time.

When the owner goes out of scope, the value will be dropped.

Variable Scope

Variable scope is managed with {} braces.

Memory and Allocation

Oh interesting! Rust prevents double frees by ensuring that pointers are one to one from references to heap data.

Stack-Only Data

I wonder how the constraint that tuples composed of Copy-trait types have the Copy-trait is implemented. Like is it done manually up to a certain arity like Haskell with tuples and Functor? Or recursively somehow like Purescript?

Return Values and Scope

There’s a neat purity to how Rust handlies pointers and scope here.

References and Borrowing

Mutable References

Interested in better understanding what lifetimes do.

The Rules of References

At any given time, you can have either (but not both of) one mutable reference or any number of immutable references.

References must always be valid.

The Slice Type

What if we have two overlapping slices? I guess that’s why slices have to be immutable?

It’s neat that string literals are slices of the binary.