Example of using Default::default with a struct

[insanitybit]

The book currently suggests that Default::default is useful for when you want to be generic over construction, but I would argue that that's rarely why you want default, and instead that use case is much better satisfied by taking a closure.

Instead, I think Default is almost exclusively useful for cases like this:

let some_val = MyStruct {
  val_a: 1234,
  ..Default::default()
};

let other_val = MyStruct {
  val_c: "other thing",
  ..some_val,
};

There are some cases where 'default' construction is used as a generic, like on Option::unwrap_or_default, but unsurprisingly I see unwrap_or and unwrap_or_else used far more often.