Access Specifiers¶

On the previous pages (Classes and Objects and Tutorials), you may have noticed in our fields structure, it contains the fields such as public, private, and protected.

In Ignition, Access Specifiers are the rules of engagement for your class data. They define who is allowed to see or modify a member, enforced at runtime by library internals such as the StackSpider and our custom env.

By categorizing members into these three scopes, you create a "blackbox" architecture, exposing only what is necessary and protecting the internal state of your logic.

Public Access SpecifierPrivate Access SpecifierProtected Access Specifier

The public specifier is the front door of your class. Members defined here are accessible from anywhere in your project.

class "Entity" {
    public = {
        Health = 100
    }
}

-- Accessible from an external script
print(entity.Health) -- 100

The private specifier is top secret. These members are strictly encapsulated within the specific class that defined them. Not even children can see them. Friended functions can also access private members so long as it was explicitly defined.

class "Entity" {
    private = {
        CurrentState = "Idle"
    }
}

-- Some external script or line of code
print(entity.CurrentState) -- ERROR (attempt to access private property "CurrentState")

The protected specifier is for "Family Members Only." These members are hidden from the outside world but are shared with any class that inherits from this one.

class "Entity" {
    protected = {
        Move = func {}
    }
}
-- Some derived class
entity:Move(Vector3.new(0, 0, 10)) -- Moves by 10 studs on the +Z Axis
-- Some external script or line of code
entity:Move(Vector3.new(0, 0, 10)) -- ERRORS (attempt to access protected property "Move")

Note

Child classes can read/write protected properties of their parents, however, parent classes themselves cannot view the protected or private members of their children themselves!

Access flows up the inheritance chain, never down.

Summary of Permissions

Accessor	Public	Protected	Private
Same Class	✅	✅	✅
Derived (Child) Class	✅	✅	❌
External Scripts	✅	❌	❌

Access vs. Exposure

You might later learn about the exposure field of the functions property and func (concepts later discussed).

The difference between the two is that exposure is about Network Visibility (if the member can be visible on that network context, i.e., you only want the Accessories property of an Entity appear on the client), having server, client, and shared.