Theme persistance

[antoniorodr]

Hello!

Does Textual offer an event or method to retrieve the theme selected by the user in the palette menu? I'm trying to make the theme persist across sessions.

Thanks!

[willmcgugan]

App.theme

[antoniorodr]

So when the user changes the theme from the palette menu, I can retrieve the value using App.theme?

[willmcgugan]

Exactly. theme is also a reactive, so you could watch it for changes.

[antoniorodr]

I am sorry @willmcgugan , could you give me an example? I am pretty new to programming :)

I've this method into the App class. cfg is just a BaseModel which defines the config model for the app, and set_theme writes the new theme into a file which will be retrieved in the on_mount method.

    def update_theme(self, new_theme: str) -> None:
        self.theme = new_theme
        self.cfg.set_theme(new_theme)
        self.refresh()

But this update_theme does not seems to be getting the new theme value.

[willmcgugan]

Implement a watch method which is called when the theme changes.

i.e. in App:

def watch_theme(self, theme:str):
    self.cfg.set_theme(theme)

No need to call refresh.

[antoniorodr]

I needed to add this too (in on_mount)

self.theme_changed_signal.subscribe(self, self._on_theme_changed)

Don't know if its the right way to do it, but it works 🤣

[davidfokkema]

Why the _on_theme_changed? Did you copy Will’s code? If you define a watch_theme() method in the App class, that’s the one that is automatically called by Textual when the theme changes. No need to subscribe to signals yourself. See e.g. https://textual.textualize.io/guide/reactivity/#watch-methods.

[antoniorodr]

Yeah you are right. It was my fault, I did not change the name of the function to watch_theme

Thanks!

[willmcgugan]

@antoniorodr Both methods work, but you only need one or the other, not both. I'd go for App.watch_theme myself. But the signal could be useful if you need to listen for changes somewhere other than App.