Support dyn `Progress` - Githubissues

I would like to add another provided method to Progress, suitable for trait-object usage to avoid monomorphization:

triat DynProgress: Send + Sync {
    // Required methods
    fn add_child(&mut self, name: String) -> BoxedDynProgress;
    fn add_child_with_id(
        &mut self,
        name: String,
        id: Id
    ) -> BoxedDynProgress;
    fn init(&mut self, max: Option<Step>, unit: Option<Unit>);
    fn set(&mut self, step: Step);
    fn step(&self) -> Step;
    fn inc_by(&mut self, step: Step);
    fn set_name(&mut self, name: String);
    fn name(&self) -> Option<String>;
    fn id(&self) -> Id;
    fn message(&self, level: MessageLevel, message: String);

    // Provided methods
    fn unit(&self) -> Option<Unit> { ... }
    fn max(&self) -> Option<Step> { ... }
    fn set_max(&mut self, _max: Option<Step>) -> Option<Step> { ... }
    fn inc(&mut self) { ... }
    fn counter(&self) -> Option<StepShared> { ... }
    fn info(&self, message: String) { ... }
    fn done(&self, message: String) { ... }
    fn fail(&self, message: String) { ... }
    fn show_throughput(&self, start: Instant) { ... }
    fn show_throughput_with(
        &self,
        start: Instant,
        step: Step,
        unit: Unit,
        level: MessageLevel
    ) { ... }
}

/// An opaque type so that `gix` can internally change its implementation details,
/// e.g. use an `Arc` instead of `Box`, or even inlining the progress.
pub struct BoxedDynProgress;

impl BoxedDynProgress {
    pub fn new<P: Progress>(p: P) -> Self;
}

impl DynProgress for BoxedDynProgress {
    // ...
}

impl Progress for BoxedDynProgress {
    type SubProgress = Self;

    // ...
}

trait Progress {
    // ...

    // Provided method
    fn into_dyn_progressive(&mut self) -> DynProgressRef<&mut Self>;
}

pub struct DynProgressRef<'_, T>;

Originally posted on https://github.com/Byron/gitoxide/issues/987

Byron / prodash

Support dyn `Progress` #21