Struct decomposer idiom

[mihaigalos]

Hi,

I've seen this idiom before and thought maybe we could incorporate it into this repo:

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Config {
    pub finish_login_url: RedirectUrl,
    pub post_auth_url: String,
    pub provider: Provider,
    pub scopes: HashSet<Scope>,
    pub session_keys: SessionKeys,
}

impl Config {
    pub async fn discover(self) -> Result<Data<Client>, DiscoveryError<HttpClientError>> {
        let Config {
            finish_login_url,
            post_auth_url,
            provider:
                Provider {
                    client_id,
                    client_secret,
                    discover_url,
                },
            scopes,
            session_keys,
        } = self;
        let provider_metadata = CoreProviderMetadata::discover_async(discover_url, async_http_client).await?;
        let client = CoreClient::from_provider_metadata(provider_metadata, client_id, client_secret)
                         .set_redirect_uri(finish_login_url);

Creating an anonymous Config object decomposes self into the structure fields.
This essentially eliminates the need for self. every time we access a member variable.

[simonsan]

It's a nice feature for sure, but as it's already in the book I'm not sure if it would make sense to write something here which wouldn't give more information about it essentially.

[mihaigalos]

I don't remember reading this a couple of years back when I read the book. Seems they're named "Destructing Structs". Ok to skip then.