ForKeys

Import Weave.ForKeys from the Weave module.

local Weave = require(ReplicatedStorage.Weave)
local ForKeys = Weave.ForKeys

ForKeys transforms each key from a table into an Instance

local data = Value.new({Red = "foo", Blue = "bar"})
local screenGui = PlayerGui.ScreenGui

ForKeys(names, function(name)
    return Attach(TextLabel:Clone()) {
        Text = name,
        Parent = screenGui
    }
end)

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Usage

ForKeys functions takes

1. A Weave Computed or Value table.

2. A function that returns an Instance

local playerNames = Value.new({Red = "foo", Blue = "bar"})

ForKeys(playerNames, someFunction)

Where someFunction:

• Receives a value from the table

• Returns an Instance

ForKeys(playerNames, function(name)
    local textLabel = TextLabel:Clone()

    return Attach(textLabel) {
        Text = playerName,
        Parent = ScreenGui
    }
end)

---

Advanced: Optimisations

Optional

You don't have to memorise these optimisations to use ForKeys, but it can be helpful if you have a performance problem.

ForKeys will try and reuse as much as possible to improve performance.

Rather than creating a new output table from scratch every time the input table is changed.

For example, let's say we're converting an array to a dictionary:

local array = Value.new({ Nevermore = true, Knit = false, Matter = false})
ForKeys(array, function(index)
    return "Framework: " .. index
end)

print(dict:get()) --> { "Framework: Nevermore", "Framework: Knit", "Framework: Matter"}

Keys are only added or removed as needed:

local array = Value.new({ Nevermore = true, Knit = false, Matter = false})
ForKeys(array, function(index)
    return "Framework: " .. index
end)

print(dict:get()) --> { "Framework: Nevermore", "Framework: Knit", "Framework: Matter"}

array:set({ Roact = true })
print(dict:get()) --> { "Framework: Roact" }

ForKeys takes advantage of this - when a value changes, it's copied into the output table without recalculating the key. Keys are only calculated when a value is assigned to a new key.