Fantom - Basics by Example

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Continue with the Basics by Example; today's version of the post written in Fantom Enjoy!

You can copy and paste the code below in your favorite IDE/Editor and start playing and learning with it. This little "working" program will teach you the basics of the Programming Language.

There are some "comments" on the code added just to tell you what are or how are some features called. In case you want to review the theory, you can read my previous post, where I give a definition of each of the concepts mentioned on the code. You can find it here: http://carlosqt.blogspot.com/2010/08/new-series-languages-basics-by-example.html 


Greetings Program - Verbose

// Fantom Basics
internal class Greet  
{
    // Fields or Attributes
    private Str? message  
    private Str? name 
    private Int? loopMessage 
    // Properties, Getters and Setters
    public Str Message
    { 
      get { return this.&message }
      set { this.&message = this.capitalize(it) }
    }
    public Str Name
    { 
      get { return this.&name }
      set { this.&name = this.capitalize(it) }
    }
    public Int LoopMessage
    { 
      get { return this.&loopMessage }
      set { this.&loopMessage = it }
    }
    // Constructor
    public new make()
    {   
        this.message = ""
        this.name = ""
        this.loopMessage = 0
    }  
    // Overloaded Constructor
    // No Overloaded Constructor support as designed
    // Method 1
    private Str capitalize(Str val)
    {
        // "if-then-else" statement  
        if (val.size() >= 1) {  
            return val.capitalize()
        }  
        else  {  
            return ""
        }  
    }
    // Method 2
    public Void salute() 
    {  
        // "for" statement
        for (i:=1; i<=this.loopMessage; i++) 
        {  
            echo("$this.message $this.name!")  
        }  
    }  
    // Overloaded Method
    // No Overloaded Methods Support in Fantom. News methods instead.
    // Method 2.1  
    public Void salute21(Str message, Str name, Int loopMessage) 
    {  
        // "while" statement  
        Int i := 0
        while(i < loopMessage) 
        {  
            echo("${this.capitalize(message)} ${this.capitalize(name)}!")            
            i++
        }  
    }  
    // Method 2.2
    public Void salute22(Str name) 
    {
        // "switch/case" statement  
        DateTime dtNow := DateTime.now();
        switch(dtNow.hour)
        {
            case 6: case 7: case 8: case 9: case 10: case 11:  
                this.message = "good morning," 
            case 12: case 13: case 14: case 15: case 16: case 17:  
                this.message = "good afternoon,"
            case 18: case 19: case 20: case 21: case 22:  
                this.message = "good evening," 
            case 23: case 0: case 1: case 2: case 3: case 4: case 5:  
                this.message = "good night,"
            default:
                this.message = "huh?" 
        }
        echo("${this.capitalize(this.message)} ${this.capitalize(name)}!")            
    }
}  

// Console Program
public class FanGreetProgram  
{  
    public static Void main()  
    {  
        // Define variable object of type Greet and Instantiate. Call Constructor
        Greet g := Greet.make()
        // Call Setters
        g.Message = "hello"
        g.Name = "world"
        g.LoopMessage = 5
        // Call Method 2    
        g.salute()  
        // Overloaded Method 2.1 and Getters    
        g.salute21(g.Message, "fantom", g.LoopMessage)   
        // Overloaded Method 2.2    
        g.salute22("carlos")  

        // Stop and exit    
        echo("Press any key to exit...")
        console := Env.cur
        userInput := console.in.readLine
    }  
}

Greetings Program - Minimal

// Fantom Basics
class Greet  
{
    // Fields or Attributes
    private Str? message  
    private Str? name 
    private Int? loopMessage 
    // Properties, Getters and Setters
    Str Message
    { 
      get { return &message }
      set { &message = capitalize(it) }
    }
    Str Name
    { 
      get { return &name }
      set { &name = capitalize(it) }
    }
    Int LoopMessage
    { 
      get { return &loopMessage }
      set { &loopMessage = it }
    }
    // Constructor
    new make()
    {   
        message = ""
        name = ""
        loopMessage = 0
    }  
    // Overloaded Constructor
    // No Overloaded Constructor support as designed
    // Method 1
    private Str capitalize(Str val)
    {
        // "if-then-else" statement  
        if (val.size >= 1) {  
            return val.capitalize
        }  
        else  {  
            return ""
        }  
    }
    // Method 2
    Void salute() 
    {  
        // "for" statement
        for (i:=1; i<=loopMessage; i++) 
        {  
            echo("$message $name!")  
        }  
    }  
    // Overloaded Method
    // No Overloaded Methods Support in Fantom. News methods instead.
    // Method 2.1  
    Void salute21(Str message, Str name, Int loopMessage) 
    {  
        // "while" statement  
        Int i := 0
        while(i < loopMessage) 
        {              
            echo("${capitalize(message)} ${capitalize(name)}!")
            i++  
        }  
    }  
    // Method 2.2
    Void salute22(Str name) 
    {
        // "switch/case" statement  
        DateTime dtNow := DateTime.now;
        switch(dtNow.hour)
        {
            case 6: case 7: case 8: case 9: case 10: case 11:  
                message = "good morning," 
            case 12: case 13: case 14: case 15: case 16: case 17:  
                message = "good afternoon,"
            case 18: case 19: case 20: case 21: case 22:  
                message = "good evening," 
            case 23: case 0: case 1: case 2: case 3: case 4: case 5:  
                message = "good night,"
            default:
                message = "huh?" 
        }
        echo("${capitalize(message)} ${capitalize(name)}!")
    }
}  

// Console Program
class FanGreetProgram  
{  
    static Void main()  
    {  
        // Define variable object of type Greet and Instantiate. Call Constructor
        Greet g := Greet()
        // Call Setters
        g.Message = "hello"
        g.Name = "world"
        g.LoopMessage = 5
        // Call Method 2    
        g.salute
        // Overloaded Method 2.1 and Getters    
        g.salute21(g.Message, "fantom", g.LoopMessage)   
        // Overloaded Method 2.2    
        g.salute22("carlos")  

        // Stop and exit    
        echo("Press any key to exit...")
        console := Env.cur
        userInput := console.in.readLine
    }  
}

And the Output is:

Emulating Overloaded Constructor in Fantom
Fantom does not support Overloading Constructors by design, but you can some how "emulate" it by calling the constructor with an initializers list as shown here below.

class Greet  
{
    // defining public fields
    Str? message  
    Str? name 
    Int? loopMessage
    // Constructor
    new make()    
    {   
        echo("greet.make")
        message = "empty_message"
        name = "empty_name"
        loopMessage = 0
    }          
    // Method 2  
    Void Salute()  
    {  
        echo("$this.loopMessage $this.message $this.name!")
    }  
}  

class Program  
{  
    static Void main()  
    {  
        // calling constructor (printing greet.make)
        Greet g := Greet()        
        g.Salute()
        // calling constructor (printing greet.make) and explicitly assigning values to each field
        // this can be done if the fields are defined as public 
        // or you will get a Private field xxx not accessible
        Greet g2 := Greet{ message="hello"; name="world"; loopMessage=5 }
        g2.Salute()
    }  
}

And the Output is: