GitBook: [master] 2 pages modified

README.md

@@ -1,2 +1,64 @@
-# Initial page
+# Thought dump
+
+### Data + Vtable
+
+We need to get a basic grasp of this to be able to understand how we implement a Waker.
+
+Next concept is `Pin`. What guarantee do we give/get?
+
+* Not too deep into `Pin`, the real need for this trait relates to the internals of `Future`and Async/Await implementation which is another 200 lines of .... book. Interesting but really an implementation detail.
+* Next book, talk about dtolnay's `await!`macro. Check if it's feasable to make our own to see what the compiler really does. Why `Pin`is needed.
+
+### TODO:
+
+* Find Rfc's to point to for more information about concepts. also to double check my conclusions.
+
+Run this code in the playground:
+
+```rust
+use std::rc::Rc;
+
+fn main() {
+    use std::mem::size_of;
+
+    println!("Size of Box<i32>: {}", size_of::<Box<i32>>());
+    println!("Size of &i32: {}", size_of::<&i32>());
+    println!("Size of &Box<i32>: {}", size_of::<&Box<i32>>());
+    println!("Size of Box<Trait>: {}", size_of::<Box<MyTrait>>());
+    println!("Size of &dyn Trait: {}", size_of::<&dyn MyTrait>());
+    println!("Size of Rc<i32>: {}", size_of::<Rc<i32>>());
+    println!("Size of Box<Rc<i32>>: {}", size_of::<Box<Rc<i32>>>());
+    println!("Size of Rc<Trait>: {}", size_of::<Rc<MyTrait>>());
+    println!("Size of &[i32]: {}", size_of::<&[i32]>());
+    println!("Size of &[&dyn Trait]: {}", size_of::<&[&dyn MyTrait]>());
+    println!("Size of [i32; 10]: {}", size_of::<[i32; 10]>());
+    println!("Size of [&dyn Trait; 10]: {}", size_of::<[&dyn MyTrait; 10]>());
+}
+
+trait MyTrait {
+    fn do_something(&self) {
+        println!("See, something");
+    }
+}
+```
+
+### Smart pointers = Data + Vtable
+
+### Dynamic Dispatch - short intro
+
+For more information about this:
+
+{% embed url="https://alschwalm.com/blog/static/2017/03/07/exploring-dynamic-dispatch-in-rust/" %}
+
+Create our own "fat pointer". We need to do this when we create Wakers anyway so let's get to know them a little. It's probably the thing that's most difficult implementation wise.
+
+
+
+### Bonus - pointer types
+
+Normal pointer: just a memory location. Basic pointer type we all know \(reference/pointer\)
+
+Fat pointer: pointer plus some other information \(slice length, a second pointer to trait information for a trait object\). 16 byte pointer, not only compiler "hint".
+
+Smart pointer: a pointer-like type that add behaviour or restrictions eg `Box` deallocates when dropped, `Rc` tracks how many shared owner there currently are. Compiler only!