The mutability of the API 0.6.4, is it by design?

[Forsworns]

I found that the LinuxMemory is without setter, is this by design?

BTW, the current API returns an immutable reference to the struct fields, making it hard to revise the spec in place. Why not simply return a mutable reference, so that we can use get_or_insert to modify it.

For example, I have a mutable referenced spec s and want to only modify its cpu quota in palce. With current API (v0.6.4), I have to write the following code, right?

let mut linux = s.linux().clone().unwrap_or_default();
let mut resources = linux.resource().clone().unwrap_or_default();
let mut cpu = resources.cpu().clone().unwrap_or_default();
cpu.set_quota(Some(new_cpus));
resources.set_cpu(Some(cpu));
linux.set_resources(Some(resources));
s.set_linux(Some(linux));

So complicated :(

[Forsworns]

Friendly ping @utam0k

[utam0k]

@Forsworns Why don't you use a builder pattern like that?
https://github.com/containers/youki/blob/9e5516346b7a0ed6b59967a164ecabe5ca1a38ee/tests/integration_test/src/tests/example/hello_world.rs#L9-L20

[Forsworns]

@utam0k Thanks, but I only want to modify a single field of existing spec, as described above, the spec.linux.resource.cpu.quota.
It is nested so deep that it seems not a good choice to use the builder pattern, I have to copy each attribute of thespec to a new builder. Do I misunderstand something?

SpecBuilder::default()
        .root(s.root().unwrap_or_default())
        .process(
            s.process().unwrap_or_default()
        )
        .linux(
               LinuxBuilder::default()
                      .resources(
                                 LinuxResourceBuilder::default()
                                         .cpu(...)
                                 ...
                      )
                      ...
               ).build()?
        )
        ...
        .build()
        .context("failed to create spec")

[Forsworns]

I guess simply appending a get_mut="pub" to the current getset attributes is enough.
I can take this if you think it's worthwhile to do so. @utam0k