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Problems with borrowing Traits (lemmy.world)
submitted 3 years ago by djtech@lemmy.world to c/rust@programming.dev
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crosspostato da: https://lemmy.world/post/1916287

Hi everybody, I'm new to Rust.

So, I have a struct Panel which contains a data widget which implements the trait Widget I have to implement a function for Panel that uses another function that requires a type that implements Widget.

I tried Box<T>, Rc<T>, Box<dyn Widget, &T, but nothing, always compiler errors.

How can I fix this?

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[-] djtech@lemmy.world 1 points 3 years ago

Yes, obviously, but there are de-referincing/borrwowing/trait problem.

If you want to check the Trait: https://docs.rs/ratatui/latest/ratatui/widgets/trait.Widget.html

If you want to check what function do I need to run: https://docs.rs/ratatui/latest/ratatui/terminal/struct.Frame.html#method.render_widget

So the struct is something like struct Panel<T: Widget> { data: T } (tried also with Box, Rc, &mut T and Box

I need to implement a method for Panel which simply uses the function linked above. (so just asks for a Frame, the Rect type is generated by my other function)

[-] anlumo@feddit.de 3 points 3 years ago

That function takes ownership of the Widget, there's no borrowing here. Maybe that's the problem, that you're passing a reference instead of the actual object?

So, if you have a Panel containing the Widget, the function you're calling render_widget in has to take self, not &self or &mut self.

Alternatively, you can use data: Option<T> in Panel, let the function take &mut self and then use self.data.take() to move it out of self.

[-] djtech@lemmy.world 2 points 3 years ago

I checked the code and noticed that I wrote &self as the parameter 🤦🏻

Now everything works. Thanks man

[-] manpacket@lemmyrs.org 1 points 3 years ago

Showing the code and the errors compiler gives to you would help a bunch.

[-] akash_rawal@lemmy.world 1 points 3 years ago

Seems like data: T or data: &'a mut T should work for you. Your function should be accepting mut self or &mut self.

this post was submitted on 21 Jul 2023
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