Lessons in Rust: Part 1

I watched some videos today and here are some notes I took:

  • A function not ending in a semicolon being a expression versus a statement is odd.
  • A function having a return statement can end in semicolon and be an expression.
  • Stack is LIFO. Stack can only hold data of a fixed size. A double quoted string is fixed length. A String::from is dynamic length and stored on the Heap.
  • When a value is put in the Heap, the Heap is searched for space large enough to hold the element (out of order, versus the Stack always in LIFO order).
  • All Heap values have a ‘pointer’ value in the Stack.
  • When a variable is passed into a function the function takes ‘ownership’ of the variable. Three ways to ‘fix’ this issue:
    • Clone traight, potentially performance impacting.
    • Copy traight (which requires Clone traight). Copy is explicit and Clone is implicit (in the way its called .clone() versus not).
    • Use a READ_ONLY_REFERENCE of a variable using the “&” on the parameter name.
  • With variables to functions, the MUTABLE_REFERENCE can only be applied once, versus the READ_ONLY_REFERENCE which can have many.
  • Lifetimes
    • Begin with a single quote.
    • Are only relevant for references.
    • They dont change the lifetimes of the parameters.
    • They can be inferred

I found these videos interesting: