Bindings

Bindings allow providers to have interal methods executed externally, past the Service layer. Let's look at an example:

Here we have two providers, one consumer providers that reacts to the vendor provider, and the vendor provider that emits a reaction to the consumer provider.

local Consumer = Glue.Provider("Consumer1")

function Consumer:valueChanged(value: string)
    print("New value ->", value)
end

local Vendor = Glue.Provider("Vendor")

function Vendor:onCreate()
    self.value = "Foo"
end

function Vendor:onStart()
    self:changeValue("Bar")
end

function Vendor:changeValue(value: string)
    self.value = value
end

So how do we get the two consumers to react to the vendor provider? Enter Bindings. Bindings are a way to bind a provider to a consumer. Well, how do we bind a provider to a consumer?

To create a binding, you use the createBinding function, that gets passed into Provider.onConfig. The key of the binding specifies the name of the binding. createBinding returns a symbol, that gets resolved after Provider.onCreate.

function Vendor:onConfig(bindTo, createBinding)
    self.valueChanged = createBinding()
end

Well, now we created the binding, how do we emit it though? It's pretty simple, the Binding Symbol resolves to a function, so we can simply call it like so:

function Vendor:changeValue(value: string)
    self.value = value
    self.valueChanged(value)
end

If we run this nothing will happen, since we haven't bound the consumer to the vendor provider directly. This step is vital in security so the developer can directly control method invocation. Here's how that looks like:

function Consumer:onConfig(bindTo, createBinding)
    bindTo("Vendor")
end

The string passed to bindTo must be the name of the provider you are binding to. If the provider does not exist, glue will throw an error.

Full Example

Vendor.lua

local Vendor = Glue.Provider("Vendor")

function Vendor:onConfig(bindTo, createBinding)
    self.valueChanged = createBinding()
end

function Vendor:onCreate()
    self.value = "Foo"
end

function Vendor:onStart()
    self:changeValue("Bar")
end

function Vendor:changeValue(value: string)
    self.value = value
    self.valueChanged(value)
end

Consumer.lua

local Consumer = Glue.Provider("Consumer")

function Consumer:onConfig(bindTo, createBinding)
    bindTo("Vendor")
end

function Consumer:valueChanged(value: string)
    print("New value from Consumer:", value)
end

Bindings

Full Example​

Full Example