Setting length to `None` to change a bar to a spinner, and back

[azriel91]

Heya, would allowing a progress bar's length to be set to None be a sensible thing to support?

Currently ProgressBar::set_length takes len: u64, and internally sets its state's length to Some(len). In my usage of indicatif, I want to:

• Render some progress bars, being "empty bars"
• Render progress bars during a first execution to discover units of work.
• When the units of work are discovered, I'd like to set the length of a progress bar to None or Some(len), depending on the discovered work.

That said, as it stands, I think I could achieve the same effect by removing and adding bars, instead of reusing an existing bar.

[djc]

Yeah, I'm not sure it makes sense to support this use case. You could instead set the length to 0, or remove/add bars as needed.

[azriel91]

cool thanks!