add `insert` and `insert_with` to `Option`

This removes a cause of `unwrap` and code complexity.

This allows replacing

```
option_value = Some(build());
option_value.as_mut().unwrap()
```

with

```
option_value.insert(build())
```

or

```
option_value.insert_with(build)
```

It's also useful in contexts not requiring the mutability of the reference.

Here's a typical cache example:

```
let checked_cache = cache.as_ref().filter(|e| e.is_valid());
let content = match checked_cache {
	Some(e) => &e.content,
	None => {
	    cache = Some(compute_cache_entry());
	    // unwrap is OK because we just filled the option
	    &cache.as_ref().unwrap().content
	}
};
```

It can be changed into

```
let checked_cache = cache.as_ref().filter(|e| e.is_valid());
let content = match checked_cache {
	Some(e) => &e.content,
	None => &cache.insert_with(compute_cache_entry).content,
};
```

0 files changed, 0 insertions, 0 deletions