Components

Components are the building blocks of every view. They live in presentation/ui and its subpackages, and each one implements core.View. The pages are grouped into:

Fluent builders

A constructor like VStack or Text returns a component value, a struct prefixed with T (TStack, TText). You configure it by chaining methods. Every method works on a copy and returns the modified copy:

func greeting(name string) core.View {
	return VStack(
		Text("Hello").Font(HeadlineMedium),
		Text(name),
	).Alignment(Leading).
		Gap(L8).
		Padding(Padding{}.All(L16))
}

Because components are plain values, a method never changes the receiver. Assign the result if you build a component step by step:

stack := HStack(Text("A"), Text("B"))
stack.Gap(L16)         // no effect, the result is discarded
stack = stack.Gap(L16) // correct

The same applies to styling values like Padding, Frame and Border: Padding{}.All(L16) starts with the zero value and returns a new one.

Where a chain ends

Some methods return the interface DecoredView instead of the concrete type, typically Padding, Frame, WithFrame, Border, Visible and AccessibilityLabel. After such a call only the methods of DecoredView are left, so call them last:

VStack(Text("A")).
	Gap(L8).                     // TStack
	BackgroundColor(M4).         // TStack
	Padding(Padding{}.All(L16)). // DecoredView from here on
	Border(Border{}.Radius(L8))  // DecoredView

VStack(...).Padding(...).Gap(L8) does not compile, because DecoredView has no Gap method. The method tables on the component pages show the return type where it is not the component itself.