Rustlings: Live!
Goals:
Share knowledge
Ask Questions
Pair
Grow
Social Rules
https://www.recurse.com/manual
Have Fun!
Rust's Ownership Model
Memory Management
| Techniques of memory Management | Languages |
|---|---|
| Garbage Collection | Java, .Net, Ruby, Python, JS |
| Explicit Memory Allocation | C, C++ |
| Ownership | Rust 🦀 |
Memory Management
What is memory safety?
Memory safety is the property of a program where memory pointers used always point to valid memory, i.e. allocated and of the correct type/size. Memory safety is a correctness issue—a memory unsafe program may crash or produce nondeterministic output depending on the bug.
-- Will Crichton
dangling pointers:
Pointers that point to invalid data
double frees:
Trying to free the same memory location twice
Memory Management
Heap
Stack
Stacks
Last In
First Out
Fixed size
Heaps
Any arbitrary size
Allocate space
Identifiableaddress
Stack vs Heap
| Data Types | |
|---|---|
| Stack | booleans, characters, integers |
| Heap | strings, lists, arrays and other collections |
All values in Rust are stack allocated by default. Values can be boxed (allocated on the heap) by creating a Box<T>
Rules of Ownership
-
1 variable => 1 owner
-
1 Owner!Â
-
Variable is only valid when owner is in scope
Variable Scope
"Moving" Ownership
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| index | value |
|---|---|
| 0 | h |
| 1 | e |
| 2 | l |
| 3 | l |
| 4 | o |
| index | value |
|---|---|
| 0 | h |
| 1 | e |
| 2 | l |
| 3 | l |
| 4 | o |
Not how rust works
S1
S2
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| index | value |
|---|---|
| 0 | h |
| 1 | e |
| 2 | l |
| 3 | l |
| 4 | o |
How rust works
S1
S2
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| name | value |
|---|---|
| pointer | |
| len | 5 |
| capacity | 5 |
| index | value |
|---|---|
| 0 | h |
| 1 | e |
| 2 | l |
| 3 | l |
| 4 | o |
How rust works
S1
S2
let s1 = String::from("hello");
let s2 = s1;
println!("{}", s1);
Ownership: "shallow copy"
Ownership in Functions
Ownership in Functions
Rules of Ownership
-
Begins with Assignment
-
Ends with scope
-
Moves with reassignment
References and Borrowing
References and Borrowing
Mutable References
Let's Pair!
Rustlings
https://github.com/rust-lang/rustlings
Rustlings
Move Semantics
$ rustlings run move_semantics1
$ rustlings hint move_semantics1
Complete Exercises
1, 2, 3, 4