Set

Syntax:

setname {
  property1;
  ...//some properties
  @method1(parameters) {
    ...//statements
  }
  ...//some methods
}

Actually set is very like structure in C. It has property definition, but Melang also supports method definition in Set.

Property in Set is a kind of variable. Method is a kind of function.

e.g.

human {
  name;
  age;
  gender;
  @init (name, age, gender)
  {
    this.name = name;
    this.age = age;
    this.gender = gender;
  }
}

human is a set name. It has some properties: name, age, gender, score. And one method: init.

In this example, you can see:

• property definition just need a name
• method definition has a special local variable named this

this is an internal variable in method. It is a reference to set’s object.

Now we have two questions:

1. What is object
2. What a set definition can do

Set is an abstract definition and object is a instantiated Set.

As shown above, set human is a definition. It defines some basic attributes of a human.

So if there is a boy named Tom, and he also has these attributes, then he is an instance of set human, which means Tom is an object of set human.

So how to instantiate a set object?

Tom = $human;

That’s done. Now, we have a variable named Tom, and that is an object of set human.

Now, we can visit Tom’s properties and methods.

sys = Import('sys');

Tom.init('Tom Moore', 8, 'male');

sys.print(Tom.name);

The first line is calling method init, this method initiates object Tom’s properties.

The last line outputs Tom’s name.

And we can see, if we want to visit an object’s property or method, we need to use operator . (dot). Left of operator . is an object and right is object’s property or method.

Back to the topic this. In this example, this is a reference of object Tom. So modifications on this will directly affect on Tom. So the result of the last one statement is ‘Tom Moore’.