Skip to main content

Batching

Val supports batching, where we can set multiple states in a batch that will only call observers after all the values have been set.

Let's look at a basic example of setting a state without batching:

local x = Val.new(2)
x:on(function(value)
	print("x set to", value)
end)
x:set(3) -- x set to 3
x:set(4) -- x set to 4
x:set(5) -- x set to 5

In this case, the observer will be called after each set. Now let's do the same thing but with batching:

local x = Val.new(2)
x:on(function(value)
	print("x set to", value)
end)

Val.batch(function(set)
	set(x, 3) -- no output
	set(x, 4) -- no output
	set(x, 5) -- no output
end) -- x set to 5

This time, setting the value of x will not call the observer until after the batch is done. This means that the observer will only be called once instead of three times.

The Val.batch function took in a callback function as the argument, which took in a set function. The set(Val<T>, T) function allows us to set the value of the state without immediately calling the observer. If Val:set were to be used inside the batch callback, then the observer would immediately be called.

note
  • You cannot use any of the assignment operator methods inside the batch, as just like Val:set, they would immediately call the observer inside the batch. You would have to set the value manually, so a:add(b) would look like set(a, a:get() + b)
  • Computeds cannot be batched because of their reliance on observers. As mentioned previously about redundant updates when chaining computeds, there is not a way to solve it with batching in Val.