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124 lines
3.2 KiB
Markdown
124 lines
3.2 KiB
Markdown
middleclass
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===========
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[](https://travis-ci.org/kikito/middleclass)
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A simple OOP library for Lua. It has inheritance, metamethods (operators), class variables and weak mixin support.
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Quick Look
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==========
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```lua
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local class = require 'middleclass'
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local Fruit = class('Fruit') -- 'Fruit' is the class' name
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function Fruit:initialize(sweetness)
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self.sweetness = sweetness
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end
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Fruit.static.sweetness_threshold = 5 -- class variable (also admits methods)
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function Fruit:isSweet()
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return self.sweetness > Fruit.sweetness_threshold
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end
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local Lemon = class('Lemon', Fruit) -- subclassing
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function Lemon:initialize()
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Fruit.initialize(self, 1) -- invoking the superclass' initializer
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end
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local lemon = Lemon:new()
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print(lemon:isSweet()) -- false
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```
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Documentation
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=============
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See the [github wiki page](https://github.com/kikito/middleclass/wiki) for examples & documentation.
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Installation
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============
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Just copy the middleclass.lua file wherever you want it (for example on a lib/ folder). Then write this in any Lua file where you want to use it:
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```lua
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local class = require 'middleclass'
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```
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Specs
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=====
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This project uses [busted](http://olivinelabs.com/busted/) for its specs. If you want to run the specs, you will have to install it first. Then just execute the following:
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```bash
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cd /folder/where/the/spec/folder/is
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busted
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```
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Performance tests
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=================
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Middleclass also comes with a small performance test suite. Just run the following command:
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```bash
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lua performance/run.lua
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```
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License
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=======
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Middleclass is distributed under the MIT license.
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Updating from 2.x
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=================
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Middleclass used to expose several global variables on the main scope. It does not do that anymore.
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`class` is now returned by `require 'middleclass'`, and it is not set globally. So you can do this:
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```lua
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local class = require 'middleclass'
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local MyClass = class('MyClass') -- works as before
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```
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`Object` is not a global variable any more. But you can get it from `class.Object`
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```lua
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local class = require 'middleclass'
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local Object = class.Object
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print(Object) -- prints 'class Object'
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```
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The public functions `instanceOf`, `subclassOf` and `includes` have been replaced by `Object.isInstanceOf`, `Object.static.isSubclassOf` and `Object.static.includes`.
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Prior to 3.x:
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```lua
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instanceOf(MyClass, obj)
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subclassOf(Object, aClass)
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includes(aMixin, aClass)
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```
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Since 3.x:
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```lua
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obj:isInstanceOf(MyClass)
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aClass:isSubclassOf(Object)
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aClass:includes(aMixin)
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```
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The 3.x code snippet will throw an error if `obj` is not an object, or if `aClass` is not a class (since they will not implement `isInstanceOf`, `isSubclassOf` or `includes`).
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If you are unsure of whether `obj` and `aClass` are an object or a class, you can use the methods in `Object`. They are prepared to work with random types, not just classes and instances:
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```lua
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Object.isInstanceOf(obj, MyClass)
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Object.isSubclassOf(aClass, Object)
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Object.includes(aClass, aMixin)
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```
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Notice that the parameter order is not the same now as it was in 2.x. Also note the change in naming: `isInstanceOf` instead of `instanceOf`, and `isSubclassOf` instead of `subclassOf`.
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