How to use a constructor

A constructor is a method (sub or function) that is executed when an object is initialized.
A constructor makes it possible to set the values of some variables at startup. Have a look at DrawingArea - How to draw some figures. It is another example that shows the use of a constructor.

The Program

The global variable X is set at startup by the constructor. If the button is clicked, it will be written in the Text property of the Label.

The Code:

 ' Gambas class file

X AS String

A variable has to be global in order for it to be visible in different methods (_new() and Button1_Click()). See How to use local and global variables.

STATIC PUBLIC SUB Main()
  DIM hForm AS Fmain
  hForm = NEW Fmain
  hForm.Show
END

PUBLIC SUB _new()
  X = "cool"
END
'The constructor is a method, called: PUBLIC SUB _new()
'Here, the global variable X is set to "cool".

PUBLIC SUB Button1_Click()
  TextLabel1.Text = "Constructors are " & X & "!"
END

The Source

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