Problems with getting .step() to work

[pascalblanc]

Hi there,

I admit I am relatively new to all this (programming in general) so sorry if I missed on something very basic.
I tried to run different examples that make use of .step() and, whether it is examples I took from the web or my own, I always encountered
"method not found in 'Cursive' " at compile time (cursive = 0.16.0 or higher). With cursive = 0.15.0 it still worked.

After some reading of the Cursive documentation, I realised that by adding this to my code, I again have access to the siv.step() function and examples compile ok.

let mut siv = cursive::default().into_runner();

Is that the correct way of doing this? Maybe there is a "minimal working example" for usage of ".step()" that works with the latest Cursive version?

Thank you very much in advance!
Pascal

[gyscos]

Hi!

First, note that using this step() function should be considered part of the "advanced" API - in most cases, you don't need it and should be able to just call .run(). Especially if you are still learning about Cursive, rust, and programming in general, sticking to the default event loop will make your life much easier.

Now, the details.

Conceptually, a Cursive instance just describe the views configuration, the callbacks you configure, and so on. It doesn't need to be running. You could create a Cursive object without a terminal, in a daemon, or anything.

Once you actually want to start interacting with a terminal (receiving input and printing stuff) you start what you could call a "session" - this is the CursiveRunner object. As long as you have a CursiveRunner, it means the terminal is initialized and ready to be used. As soon as you drop it, the terminal is reset back to usual.
While you have this CursiveRunner, you can have it just run the event loop by itself with CursiveRunner::run(), or you can run it step-by-step yourself. In that case, you would call CursiveRunner::step() regularly, just like its run method does.

To get this runner, you can indeed use CursiveRunnable::into_runner. It will initialize the terminal with the default backend, and lets you call this step() function yourself.

I agree that this should all be better documented. Right now there's not many examples about it, mainly because it's a rather niche use.

[pascalblanc]

Thank you so much for this great and detailed explanation! It really helps me to grasp some concepts of the inner workings of Cursive that apparently I just didn't get before. I am sure I will read your reply a quite few times in the next weeks.😊
Cheers and thanks again.