rollup merge of #24672: steveklabnik/edit_tuple_structs
I thought I edited all the last little chapters, but I missed this one. r? @alexcrichton
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% Tuple Structs
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Rust has another data type that's like a hybrid between a tuple and a struct,
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called a *tuple struct*. Tuple structs do have a name, but their fields don't:
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Rust has another data type that's like a hybrid between a [tuple][tuple] and a
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[struct][struct], called a ‘tuple struct’. Tuple structs have a name, but
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their fields don’t:
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```{rust}
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```rust
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struct Color(i32, i32, i32);
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struct Point(i32, i32, i32);
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```
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[tuple]: primitive-types.html#tuples
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[struct]: structs.html
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These two will not be equal, even if they have the same values:
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```{rust}
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```rust
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# struct Color(i32, i32, i32);
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# struct Point(i32, i32, i32);
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let black = Color(0, 0, 0);
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@ -20,7 +24,7 @@ let origin = Point(0, 0, 0);
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It is almost always better to use a struct than a tuple struct. We would write
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`Color` and `Point` like this instead:
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```{rust}
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```rust
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struct Color {
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red: i32,
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blue: i32,
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@ -37,12 +41,12 @@ struct Point {
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Now, we have actual names, rather than positions. Good names are important,
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and with a struct, we have actual names.
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There _is_ one case when a tuple struct is very useful, though, and that's a
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tuple struct with only one element. We call this the *newtype* pattern, because
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There _is_ one case when a tuple struct is very useful, though, and that’s a
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tuple struct with only one element. We call this the ‘newtype’ pattern, because
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it allows you to create a new type, distinct from that of its contained value
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and expressing its own semantic meaning:
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```{rust}
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```rust
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struct Inches(i32);
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let length = Inches(10);
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@ -52,5 +56,5 @@ println!("length is {} inches", integer_length);
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```
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As you can see here, you can extract the inner integer type through a
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destructuring `let`, as we discussed previously in 'tuples.' In this case, the
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destructuring `let`, as we discussed previously in ‘tuples’. In this case, the
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`let Inches(integer_length)` assigns `10` to `integer_length`.
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