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Clarify that assigning/comparing different tuple types to one another won't compile

This commit is contained in:
Johannes Muenzel 2014-10-07 01:22:58 -04:00
parent b5ba2f5517
commit c211d132c3
1 changed files with 15 additions and 4 deletions
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src/doc/guide.md
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@ -914,12 +914,23 @@ or 'breaks up,' the tuple, and assigns the bits to three bindings.
This pattern is very powerful, and we'll see it repeated more later.
The last thing to say about tuples is that they are only equivalent if
the arity, types, and values are all identical.
There also a few things you can do with a tuple as a whole, without
destructuring. You can assign one tuple into another, if they have the same
arity and contained types.
```rust
let mut x = (1i, 2i);
let y = (2i, 3i);
x = y;
```
You can also check for equality with `==`. Again, this will only compile if the
tuples have the same type.
```rust
let x = (1i, 2i, 3i);
let y = (2i, 3i, 4i);
let y = (2i, 2i, 4i);
if x == y {
println!("yes");
@ -928,7 +939,7 @@ if x == y {
}
```
This will print `no`, as the values aren't equal.
This will print `no`, because some of the values aren't equal.
One other use of tuples is to return multiple values from a function: