Skip to content

Fix typo chapter 18.2, Quiz Answer chapter 17.4 #325

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Fix typo chapter 18.2, Quiz Answer chapter 17.4 #325

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
fc450cc
fix typos in chapter 18.2 (17-9 -> 18-9, 17-11 -> 18-11)
AthfanFasee Jul 1, 2025
4802fc6
fix typo chapter 18.2 (17-11 -> 18-11)
AthfanFasee Jul 1, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 4 additions & 4 deletions src/ch18-02-trait-objects.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -247,7 +247,7 @@ let v = vec!["Hello world"];
```

Type inference is trickier for trait objects. For example, say we tried to factor
the `components` array in Listing 17-9 into a separate variable, like this:
the `components` array in Listing 18-9 into a separate variable, like this:

```rust,ignore,does_not_compile
fn main() {
Expand All @@ -260,7 +260,7 @@ fn main() {
}
```

<span class="caption">Listing 17-11: Factoring the components array causes a type error</span>
<span class="caption">Listing 18-11: Factoring the components array causes a type error</span>

This refactor causes the program to no longer compile! The compiler rejects this program with
the following error:
Expand All @@ -280,8 +280,8 @@ error[E0308]: mismatched types
| |_____^ expected `SelectBox`, found `Button`
```

In Listing 17-09, the compiler understands that the `components` vector must have the type
`Vec<Box<dyn Draw>>` because that's specified in the `Screen` struct definition. But in Listing 17-11,
In Listing 18-09, the compiler understands that the `components` vector must have the type
`Vec<Box<dyn Draw>>` because that's specified in the `Screen` struct definition. But in Listing 18-11,
the compiler loses that information at the point where `components` is defined. To fix the issue, you
have to give a hint to the type inference algorithm. That can either be via an explicit cast on
any element of the vector, like this:
Expand Down