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## RON extensions
RON has extensions that can be enabled by adding the following attribute at the top of your RON document:
`#![enable(...)]`
# unwrap_newtypes
You can add this extension by adding the following attribute at the top of your RON document:
`#![enable(unwrap_newtypes)]`
This feature enables RON to automatically unwrap simple tuples.
```rust
struct NewType(u32);
struct Object {
pub new_type: NewType,
}
```
Without `unwrap_newtypes`, because the value `5` can not be saved into `NewType(u32)`, your RON document would look like this:
```ron
(
new_type: (5),
)
```
With the `unwrap_newtypes` extension, this coercion is done automatically. So `5` will be interpreted as `(5)`.
```ron
#![enable(unwrap_newtypes)]
(
new_type: 5,
)
```
# implicit_some
You can add this extension by adding the following attribute at the top of your RON document:
`#![enable(implicit_some)]`
This feature enables RON to automatically convert any value to `Some(value)` if the deserialized type requires it.
```rust
struct Object {
pub value: Option<u32>,
}
```
Without this feature, you would have to write this RON document.
```ron
(
value: Some(5),
)
```
Enabling the feature would automatically infer `Some(x)` if `x` is given. In this case, RON automatically casts this `5` into a `Some(5)`.
```ron
(
value: 5,
)
```
With this extension enabled, explicitly given `None` and `Some(..)` will be matched eagerly on `Option<Option<Option<u32>>>`, i.e.
* `5` -> `Some(Some(Some(5)))`
* `None` -> `None`
* `Some(5)` -> `Some(Some(Some(5)))`
* `Some(None)` -> `Some(None)`
* `Some(Some(5))` -> `Some(Some(Some(5)))`
* `Some(Some(None))` -> `Some(Some(None))`
* `Some(Some(Some(5)))` -> `Some(Some(Some(5)))`
# unwrap_variant_newtypes
You can add this extension by adding the following attribute at the top of your RON document:
`#![enable(unwrap_variant_newtypes)]`
This feature enables RON to automatically unwrap newtype enum variants.
```rust
#[derive(Deserialize)]
struct Inner {
pub a: u8,
pub b: bool,
}
#[derive(Deserialize)]
pub enum Enum {
A(Inner),
B,
}
```
Without `unwrap_variant_newtypes`, your RON document would look like this:
```ron
(
variant: A(Inner(a: 4, b: true)),
)
```
With the `unwrap_variant_newtypes` extension, the first structural layer inside a newtype variant will be unwrapped automatically:
```ron
#![enable(unwrap_newtypes)]
(
variant: A(a: 4, b: true),
)
```
Note that when the `unwrap_variant_newtypes` extension is enabled, the first layer inside a newtype variant will **always** be unwrapped, i.e. it is no longer possible to write `A(Inner(a: 4, b: true))` or `A((a: 4, b: true))`.
# explicit_struct_names
During serialization, this extension emits struct names. For instance, this would be emitted:
```ron
Foo(
bar: Bar(42),
)
```
During deserialization, this extension requires that all structs have names attached to them. For example, the following deserializes perfectly fine:
```ron
Foo(
bar: Bar(42),
)
```
However, with the `explicit_struct_names` extension enabled, the following will throw an `ExpectedStructName` error:
```ron
(
bar: Bar(42),
)
```
Similarly, the following will throw the same error:
```ron
Foo(
bar: (42),
)
```
Note that if what you are parsing is spread across many files, you would likely use `Options::with_default_extension` to enable `Extensions::EXPLICIT_STRUCT_NAMES` before the parsing stage. This is because prepending `#![enable(explicit_struct_names)]` to the contents of every file you parse would violate DRY (Don't Repeat Yourself).
Here is an example of how to enable `explicit_struct_names` using this method:
```rust
use ron::extensions::Extensions;
use ron::options::Options;
// Setup the options
let options = Options::default().with_default_extension(Extensions::EXPLICIT_STRUCT_NAMES);
// Retrieve the contents of the file
let file_contents: &str = /* ... */;
// Parse the file's contents
let foo: Foo = options.from_str(file_contents)?;
```
|
