Rust @programming.dev djtech @lemmy.world 1 yr. ago

Problems with borrowing Traits

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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7 comments

Use self.widget?

Maybe show some code of what you're trying to do.
- 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<dyn Widget>
  
  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)
  
  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.
  
  I checked the code and noticed that I wrote &self as the parameter 🤦🏻
  
  Now everything works. Thanks man
  
  Showing the code and the errors compiler gives to you would help a bunch.
  
  Seems like data: T or data: &'a mut T should work for you. Your function should be accepting mut self or &mut self.

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