How to access a custom widget's attributes from the main struct?

[Kevin]

Hello, World!

I’m creating a custom widget as described in the gtk-rs book.

How can I access CustomButton.number from the CustomButton class in mod.rs? The book doesn’t cover that because .number is only ever used in the other class (in imp.rs).

Let’s say I’m trying to add a method like

pub fn get_number(&self) -> i32 {
    // self.???
}

Here I only have access to .inner and .phantom. The former is a TypedObjectRef<CustomButton, Button>, which doesn’t give me access to a CustomButton object. The latter is a PhantomData<>, which doesn’t look like what I need.

I’ve checked the Amberol source code to see how a real-life application solves this problems, and it uses .imp(), which comes from ObjectSubclassIsExt (e.g.
src/volume_control.rs · ff850affcba6f46b1d3b7c4a42b95ab52e517ff8 · World / amberol · GitLab).

But I don’t have access to that.

It’s possible that Amberol uses a newer version of glib or GTK but even then, I assume that the version in the book also has a way to do what I’m trying to do? I tried using GTK 4.10, but no dice.

[Kevin]

I’m not sure how I didn’t realize that, but it was because I hadn’t explicitly imported the ObjectSubclassIsExt trait. So I just needed to add something like

use gtk::subclass::prelude::ObjectSubclassIsExt;

then I can do self.imp().number if the field is public.

[ebassi (Emmanuele Bassi)]

Instead of importing a single trait, you should import the whole subclass prelude:

use gtk::subclass::prelude::*;

This will avoid extra pain in the future.