Design: use and_then?

[infiniteregrets]

With and_then

let pod_label = deployment
            .spec
            .and_then(|spec| spec.template.metadata)
            .and_then(|metadata| metadata.labels)
            .and_then(|labels| labels.get("app").cloned())
            .ok_or_else(|| {
                LayerError::DeploymentNotFound(format!(
                    "Label for deployment: {}, not found!",
                    self.deployment.clone()
                ))
            })?;

Without and_then

let pod_label = || -> Option<String> {
          deployment                
          .spec?
          .template
          .metadata?
          .labels?
          .get("app")
          .cloned()
      }()
      .ok_or_else(|| {
          LayerError::DeploymentNotFound(format!(
              "Label for deployment: {}, not found!",
              self.deployment.clone()
          ))
      })?;

and_then just helps doing everything in chains, no use of ? or a closure.

we need to use closures in other places where multiple things return Option

[meowjesty]

Or maybe for this case (heavy use of Option), just try block as you've suggested.

[infiniteregrets]

do too many and_thens make code look ugly?

[eyalb181]

Is the and_thens' advantage in this example that it makes the closure unnecessary? Because the actual code we were discussing has the closure anyway, since it uses ? inside one of the and_then.

[infiniteregrets]

oh yeah sorry ignore that, the closure is not needed at all

[eyalb181]

Wait so ignore the closure in the "without and_then" option?

[infiniteregrets]

nope the code we were looking at yesterday had and_thens inside the closure, we didn't need that extra closure there