Created Mittwoch 09 Oktober 2019
Scope
{} -> after the end bracket } a function called drop() is automatically called to deallocate memory.
Variable
Each variable is a separate storage space/structure on stack. That also includes a vector to a memory space (memory on heap).
Scalars
Simple datatypes: integer, float, boolean, character (4 bytes), compound (array, tupple)
All have fixed sizes.
All are stored on the stack.
let x = 5 // Allocating space on stack
let y = x // Allocating space on stack and coping value
Copying of array depends on the members datatype. E.g [string, string, ...] musst be cloned.
Vector
Concist of an organization unit (variable) on the stack and the struct data on the heap, referenced by the variable.
The variable is the bookkeeper. Something like a specialized struct. Consists of a pointer to heap, length and max. capacity (memory size on heap).
let s1 = String::from("hello"); // Allocating space on stack for the reference and space on the heap for the data
let s2 = s1; // Allocating space on the stack and moving ownership to the new variable. s1 is invalidated. Deleted from stack. Called moving.
function(s1) // Moved ownership to function variable.
s1 = function() // Moved ownership from function variable to upper scope.
Coping data
let s2 = s1.clone(); // complete copy of variable and data.
Reference
Defined by &.
Only one mutable reference is possible (borrowable).
Mutable can't be mixed with immutable in the same scope.
let r = &s // read only
let r1 = &mut s // mutable reference
let r2 = &mut s // not possible
