Source

Sources in Vide are special objects that store a single value. They are the core of reactivity in Vide, as updates to a source can automatically update properties or other sources depending on that source.

A source in Vide can be created using source().

local source = vide.source

local count = source(0)

The value passed to source() is the initial value of the source.

The value of a source can be set by calling it with an argument, and can be read by calling it with no arguments.

count(count() + 1) -- increment source by 1

Below is an example of a stateful counter component.

local function Counter(props: { Position: UDim2 })
    local count = source(0)

    return create "TextButton" {
        Position = props.Position,
        Size = UDim2.new(200, 50),

        Text = count,

        Activated = function()
            count(count() + 1)
        end
    }
end

Each call of Counter {} will create a new counter element, each with their own independent count.

Vide detects when you assign a function to a property. This is known as binding and doing so will cause the property to automatically update whenever a source in that function is updated, by rerunning the function and assigning its return value. You can only bind non-event properties, otherwise the function is connected as the event callback.

This allows you as the programmer to not need to manually update GUI as the state of your program changes. You just define how the data maps to UI, and Vide's reactive system will surgically update any properties depending on sources that are changed.

Since sources are just functions, you can also pass external sources to components like so:

local function Text(p: {
    Text: () -> string
})
    return create "TextLabel" {
        Text = p.Text
    }
end

local text = source "hi"

Text {
    Text = text
}

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