# Objective
If a `Resource` implements `FromWorld` or `Default`, it's nicer to be
able to write:
```rust
let foo = world.get_resource_or_init::<Foo>();
```
Rather than:
```rust
let foo = world.get_resource_or_insert_with(Foo::default);
```
The latter is also not possible if a type implements `FromWorld` only,
and not `Default`.
## Solution
Added:
```rust
impl World {
pub fn get_resource_or_init<R: Resource + FromWorld>(&mut self) -> Mut<'_, R>;
}
```
Turns out all current in-engine uses of `get_resource_or_insert_with`
are exactly the above, so they've also been replaced.
## Testing
- Added a doc-test.
- Also added a doc-test for `World::get_resource_or_insert_with`.
b4071ca370