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Change String representation to actual #1817

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Feb 15, 2024
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Change String representation to actual #1817

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20 changes: 10 additions & 10 deletions src/memory-management/review.md
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Original file line number Diff line number Diff line change
Expand Up @@ -29,17 +29,17 @@ fn main() {
```

```bob
Stack Heap
.- - - - - - - - - - - - - -. .- - - - - - - - - - - - - - - -.
: : : :
Stack
.- - - - - - - - - - - - - -. Heap
: : .- - - - - - - - - - - - - - - -.
: s1 : : :
: +-----------+-------+ : : +----+----+----+----+----+ :
: | ptr | o---+---+-----+-->| H | e | l | l | o | :
: +-----------+-------+ : : :
: | capacity | 5 | : : +----+----+----+----+----+ :
: | ptr | o-+---+-----+-->| H | e | l | l | o | :
: | len | 5 | : : +----+----+----+----+----+ :
: | capacity | 5 | : : :
: +-----------+-------+ : : :
: : `- - - - - - - - - - - - - - - -'
`- - - - - - - - - - - - - -'
: : : :
`- - - - - - - - - - - - - -' `- - - - - - - - - - - - - - - -'
```

<details>
Expand All @@ -65,8 +65,8 @@ fn main() {
// String provides no guarantees about its layout, so this could lead to
// undefined behavior.
unsafe {
let (ptr, capacity, len): (usize, usize, usize) = std::mem::transmute(s1);
println!("ptr = {ptr:#x}, len = {len}, capacity = {capacity}");
let (capacity, ptr, len): (usize, usize, usize) = std::mem::transmute(s1);
println!("capacity = {capacity}, ptr = {ptr:#x}, len = {len}");
Comment on lines +68 to +69
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I wonder if it would be better to use [String::into_raw_parts](https://doc.rust-lang.org/std/string/struct.String.html#method.into_raw_parts) here? What do you think?

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Hmm, thanks for making me aware of this, I'm just learning rust, so I didn't know about it.

It's cool, that the string library has a feature for this, and it's a cool alternative.

I wouldn't go for it for two reasons:

  • weak reason: it's still unstable feature, so you have to enable it, otherwise it's a compile error
  • stronger reason: the currently demonstrated method works with any other type that one knows the representation for, so it has a bit more of an educational value, and there is ample warning there to say that this is for debugging, not for production

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Both good points!

}
}
```
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