SharedTable

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Represents a table-like data structure that can be shared across execution contexts. While it can be used for various sorts of general data storage, it is designed especially for use with Parallel Luau, where it can be used to share state across scripts parented under different Actor instances.

There are a couple idiomatic ways to communicate shared tables between scripts. One method is to store and retrieve SharedTable objects in the SharedTableRegistry. The registry lets any script in the same data model get or set a SharedTable by name. Another method is to use Actor:SendMessage() to send a shared table to another Actor inside a message.

Like a Luau table, a SharedTable object stores a set of key-value element pairs. Unlike a Luau table, only selected types of objects may be stored in a SharedTable, similar to other restrictions you'll find elsewhere in the Roblox engine.

Keys must either be (1) a string or (2) a nonnegative integer number less than 232. Other kinds of keys are not supported.

Values must have one of the following types: Boolean, Number, Vector, String, SharedTable, or a serializable data type. The ability to store a SharedTable as a value in another SharedTable permits the construction of nested and recursive data structures.

SharedTable objects are distinct and different SharedTable objects never compare equal, even if they have contents that would compare equal.

Like a Luau table, a SharedTable object may be frozen, in which case it is read-only. An attempt to modify a frozen SharedTable will raise an error. A frozen SharedTable can be created by first creating a (non-frozen, modifiable) SharedTable with the desired contents, and then calling SharedTable.cloneAndFreeze() to create a frozen clone of it.

Code Samples

Element Access
local st = SharedTable.new()

st[1] = "a"

st["x"] = true

st.y = 5



assert(st[1] == "a")

assert(st["x"] == true)

assert(st.x == true)

assert(st["y"] == 5)

assert(st.y == 5)



-- true is not a valid SharedTable key, so attempting to set that key

-- fails:

assert(not pcall(function() st[true] = 100 end))

-- A function is not a valid SharedTable value, so attempting to set a

-- value to a function fails:

assert(not pcall(function() st["f"] = function() end end))
Element Iteration
local st = SharedTable.new({"a", "b", "c"})



for k, v in SharedTable.clone(st, false) do

    print(k, ": ", v)

end



for k, v in st do

    print(k, ": ", v)

end

Summary

Constructors

Constructors

new

new

Parameters

t: table

Functions

clear

void

Parameters

st: SharedTable

Returns

void

clone

SharedTable

Parameters

st: SharedTable
deep: bool
Default Value: false

Returns

SharedTable

Code Samples

Shallow Clone
local original = SharedTable.new()

original["a"] = "original a"

original["b"] = "original b"

original["c"] = SharedTable.new()

original["c"]["d"] = "original d"



local clone = SharedTable.clone(original, false)

clone["a"] = "new a"

clone["b"] = "new b"

clone["c"]["d"] = "new d"

assert(original["a"] == "original a")

assert(original["b"] == "original b")



-- Because this was a shallow clone, original["c"] and clone["c"] are

-- the same SharedTable object.

assert(original["c"] == clone["c"])

assert(original["c"]["d"] == "new d")
Deep Clone
local original = SharedTable.new()

original["a"] = "original a"

original["b"] = "original b"

original["c"] = SharedTable.new()

original["c"]["d"] = "original d"



local clone = SharedTable.clone(original, true)

clone["a"] = "new a"

clone["b"] = "new b"

clone["c"]["d"] = "new d"

assert(original["a"] == "original a")

assert(original["b"] == "original b")



-- Because this was a deep clone, clone["c"] is a clone of original["c"];

-- they are distinct SharedTable objects.

assert(original["c"] ~= clone["c"])

assert(original["c"]["d"] == "original d")

cloneAndFreeze

SharedTable

Parameters

st: SharedTable
deep: bool
Default Value: false

Returns

SharedTable

increment

number

Parameters

st: SharedTable
key: string | number
delta: number

Returns

number

Code Samples

Increment
local st = SharedTable.new()

st["x"] = 1



local oldValue = SharedTable.increment(st, "x", 1)

assert(oldValue == 1)

assert(st["x"] == 2)



-- The value of the specified key must be a number.  If it is not a

-- number, the call will fail:

st["y"] = "test"

assert(not pcall(function() SharedTable.increment(st, "y", 1) end))

isFrozen

bool

Parameters

st: SharedTable

Returns

bool

size

number

Parameters

st: SharedTable

Returns

number

update

void

Parameters

st: SharedTable
key: string | number
f: function

Returns

void

Code Samples

Update
local st = SharedTable.new()

st["x"] = "abcd"



SharedTable.update(st, "x", function(v)

    assert(v == "abcd")

    return v .. "e"

end)



assert(st["x"] == "abcde")