GPUI View State - Modelling Navigation and Tabs with Enums

We can store the active navigation item as a string but an enum works better here. It makes sure the value can only be one of the sections supported by our app

Lets add these enums above struct App:

#[derive(Clone, Copy, PartialEq, Eq)]
enum Navigation {
    Inbox,
    MyIssues,
    ActiveIssues,
    Projects,
    Views,
}
 
#[derive(Clone, Copy, PartialEq, Eq)]
enum IssueTab {
    All,
    AssignedToMe,
    CreatedByMe,
}

We are deriving PartialEq and Eq because later we will compare the current value with every navigation item or tab. Clone and Copy will let us move these small enum values into click handlers without losing them from our application state.

One more thing, each navigation item also needs its own title and description, so add these two methods:

impl Navigation {
    fn title(self) -> &'static str {
        match self {
            Self::Inbox => "Inbox",
            Self::MyIssues => "My issues",
            Self::ActiveIssues => "Active issues",
            Self::Projects => "Projects",
            Self::Views => "Views",
        }
    }
 
    fn subtitle(self) -> &'static str {
        match self {
            Self::Inbox => "Recently updated issues",
            Self::MyIssues => "Issues currently assigned to you",
            Self::ActiveIssues => "Issues currently being worked on",
            Self::Projects => "Issues across every project",
            Self::Views => "Issues included in your saved view",
        }
    }
}

Now, lets run the project:

cargo run

The interface should look exactly the same. We have only described the possible values for now, we are not storing or using them yet.

GPUI Kit’s system monitor uses the same idea for its tabs. It represents the available tabs using a MonitorTab enum and later matches that enum while rendering the selected content in GPUI