AutoType

Automatic anonymous classes generation, meant to be used as data structures.

Baseline

Do this:

Metacello new
    baseline: 'AutoType';
    repository: 'github://maxwills/auto-type:main';
    load.

General usage information

AutoType is a system that can be used to automatically generate a class from setter expressions. The new class is not installed in the system, and is not registered in the logs.

|t name lastname|
name := 'ACleverFistName'.
lastname := 'ADissapointingLastName'.
t := AutoType new.

item := t newWith
	firstName: name;
	lastName: lastname;
	fullName: name , ' ' , lastname;
	endWith

Will create a new class with setters and getters for #firstName, #lastName, #fullName, and will return an instance of the class, ie., item responds to the the following messages: item firstName, item firstName:, item lastName, etc.

Additionaly, the generated class replies to the at:, at:put: and keysDo: messages, like dictionaries. Eg., you can use item at: #lastName put: 'newLastName'.

Why though?

Dictionaries seem to be slightly slow for some usages (Completely subjective and not tested). It is faster to access instance variables throught getters than finding keys in a dictionary, in the current implementation. Also, the notation for instantiation is a lot cleaner with AutoType.

How it works

The first time newWith is executed, it will crate a builder to define the class from the following setters received, until endWith, returning an instance of the new class with the assigned values.

After the first time, it will directly create a new instance of the auto defined class.

How to use

Dont put the AutoType new statement inside a block that is executed repeatedly.

DONT DO THIS

myCollection collect: [:each| 
	|t|
	t := AutoType new "bad usage!".
	t newWith
		firstName: (each at: 1);
		lastName: (each at: 2);
		fullName: (each at: 1) , ' ' , (each at: 2);
		endWith ]

Doing that will execute the definition logic on every iteration of the collect: method. Instead, use it like this:

DO THIS INSTEAD

|t|
t := AutoType new "placed instead in a scope out of the iteration".
	
myCollection collect: [:each| 
	t newWith
		firstName: (each at: 1);
		lastName: (each at: 2);
		fullName: (each at: 1) , ' ' , (each at: 2);
		endWith ]

This will execute the definition logic only during the first iteration, and then the new class is reused.

See AutoTypeTest >> testNominal.

To create more instances of the class, use the newWith/endWith cascade construct. Or you can also do: t type new, or if you already have an instance of your auto gereated class, you can do your_instance class new.