require'winapi.vobject'

This module defines a single-inheritance object model with virtual properties, method-overriding hooks and events.

Subclassing and instantiation protocol

At the core there’s on an user API and an implementation protocol for implementing a single-inheritance object model.

The user API is comprised of 2 functions:

• subclass(derived[, super]) -> derived
• isinstance(object, class) -> true|false

subclass() calls super:__subclass(derived) to perform the actual subclassing and returns derived. This means that each class is free to define how subclassing should be performed (copy all members to the derived class aka static inheritance, assign an __index metamethod aka dynamic inheritance, etc.). If the super class doesn’t define a __subclass method, nothing gets inherited and derived is returned untouched.

isinstance() calls object:__super() recursively until it matches the wanted class. Classes must implement __super() for this to work.

Note that there’s no API or implementation protocol for instantiation. The root class will define these.

The root object

The VObject class is the base class of every other class in winapi.

VObject implements the single-inheritance object model. This means that you can use subclass() to subclass from VObject and isinstance() on every instance or subclass of VObject.

VObject It also defines how instantiation works: calling Foo(args...) creates an instance of Foo, calls __init(self, args...) on it, and returns it.

VObject instances:

• inhert class fields dynamically
• inherit instance metamethods statically
• inherit super class fields dynamically
• inherit super class metamethods statically

Virtual properties

Virtual properties means that:

• x = foo.bar calls foo:get_bar() -> x, and
• foo.bar = x calls foo:set_bar(x).

If there’s a get_bar but no set_bar, doing foo.bar = x raises an error. These are “read-only properties”.

Generating properties in bulk

Calling Foo:__gen_vproperties({foo = true, bar = true}, getter, setter) generates getters and setters for foo and bar properties based on getter and setter such that:

get_foo(self)           calls getter(self, 'foo')
get_bar(self)           calls getter(self, 'bar')
set_foo(self, val)      calls setter(self, 'foo', val)
set_bar(self, val)      calls setter(self, 'bar', val)

API

Last updated: 4 years ago | Edit on GitHub