Introduction to Chinese Objects

Code snippets

HelloWorld example

class HelloWorldProgram extends Class is
    this () is ConsolePrintableText(
                "Hello world!",
                Console()
            ).print()
    end
end

Text class implementation

class Text extends AnyValue is
    this (symbols: Array[Symbol])
    this (text: Text) is
        this(text.symbols())
    end
    this (number: Number) is
        this(new TextFromNumber())
    end
    method symbols() : Array[Symbol] is
        return symbols
    end
end

All expressions enclosed with double quotes (") converts to Text implicitly during compilation

Printable class implementation

class Printable extends Class is
    method print() : Void
end

Console class abstraction

class Console extends Class is
    method write(text: Text) : Void
    method read() : TextStream
end

ConsolePrintableText class implementation

class ConsolePrintableText extends Printable, Text is
    var text: Text
    var console: Console
    this (symbols: Array[Symbol], console: Console) is
        this.text = Text(text)
    end
    method print() : Void is
        console.write(this)
    end
    method symbols() : Array[Symbols]
        return text.symbols()
    end
end

Shape class inheritance implementation

class Shape extends Class is
    method area() : Real
end

class Rectangle extends Shape is
    this(height: Integer)
    this(width: Integer)
    method area() : Real is
        return height.Mult(width) // Returns Real
    end
end

Eratosthenes sieve algorithm

class PrimeNumbers is
    var n: Integer
    this (n: Integer)
    method value() : List[Integer] is
        var prime : FilledArray[Boolean](n.Plus(1), true)
        prime.set(0, false)
        prime.set(1, false)
        var i : Integer(2)
        while i.LessEqual(n) loop
            if prime.get(i) then
                if i.Mult(i).Equal(n) then
                    var j : Integer(i.Mult(i))
                    while j.LessEqual(n) then
                        prime.set(j, false)
                        j.Plus(1)
                    end
                end
            end
            i.Plus(1)
        end
        i := Integer(0)
        primeNumbers : List[Integer]()
        while i.Less(prime.Length) loop
            if prime.get(i).Equals(true)
                primeNumbers.append(i)
        end
        return primeNumbers
    end
end

class FilledArray[T] extends Array[T] is
    var array: Array[T]
    this (l: Integer, fill: T) is
        var array: Array[T]
        var i: Integer(0)
        while i.Less(l) loop
            array.set(i, fill)
            i.Plus(1)
        end
        this.array = array
    end
    method ToList() : List is
        return array.ToList()
    end
    method Length() : Integer is
        return array.Integer()
    end
    method get(i: Integer) : T is
        array.Get(i)
    end
    method put(i: Integer, v: T) is
        array.Set(i, v)
    end
end

Basic Object-oriented features

Object instantiation

class Employee is
    var name: Text
    var salary: Integer
    this(name: Text, salary: Integer) throwing TooBigSalary Exception is
        if salary.Greater(200000)
            throw new class TooBigSalaryException extends Exception
        end
        this.name = name
        this.salary = salary
    end

    method work() : Text is
        return new FormattedText(
            "%s works, earning %d",
            name,
            salary
        )
    end
end

Class above can be instantiated this way

new Employee("Alice", 32).work() // -> returns "Alice works, earning 32"
new Employee("Alice", 320000).work() // -> throws TooBigSalaryException

Inheritance and Polymorphism

class Programmer extends Employee
    var employee: Employee
    this (employee)

    method work() : Text is
        return new FormattedText(
            "Programmer %s",
            employee.work()
        )
    end
end

Example of usage:

new Programmer(new Employee("Harry", 10000)).work()