Clone your form into many !!!

This is a fun code example to try. When you open up a new Application project, you get a form. To have fun, we can create hundreds of “copies” of this form! On runtime. Here’s how…

Concept

Do you know what a “Class” is? A Class is a collection of students, right? No, not in the programing world! If you know what class is, then understanding this example will be easier for you. If you don’t, then I can simply say that a class is a variable which has its own variables and functions. You can ask a class to do something and it will do it. You can say that a class has its own life - like a person! It can answer to your calls and remember things.

For example, when you create a new Application/GUI project, you see a TForm1 class declaration at the top. And a variable declaration of Form1: TForm1. Here, Form1 is a variable which holds the TForm1 class. It means that we have made a copy of the TForm1 class as Form1. If you say to the Form1 variable that hey buddy, please close yourself (Form1.close) then it closes itself. This way you can command a variable! So this is basically a class.

The beauty of class is that you can make as many “copies” of them you like. For example, you can create a class named human and you have two variables like Name and Age. So you can create new humans and name it! …and set age to it! …virtually!

Human1.Name := 'John';

Human1.Age := 25;



Human2.Name := 'Kate';

Human2.Age := 21;

And you can create as many humans like this as you want!

(I found a good introduction of classes in the php manual, but can’t find it now. It had a shopping cart class example which was very easy to understand.)

Quick Tutorial

Create an Application project. Project -> New Project -> Application -> OK.

Click the TButton from the toolbar and drag an area in the form to create a button. Double click it. Then write:

var
  frm: TForm1;

begin
  frm:=TForm1.Create(Form1);
  frm.Show;

end;

Run it!

Press F9. Click the button and a new form will appear on top each time you click the button. The problem is that new forms appear at one position. So it is difficult to understand whether a new form has appeared. Close the forms. Do the following…

With the form selected, go to Object Inspector and set Position to poDefaultPosOnly. This will position every new form  in cascading style (one lower to another).

Now again press F9. Now you will see pure fun! Forms and forms everywhere! Keep copying until your heart desires.

Downloads

You can download the source code for the tutorial project and executable/EXE files from the links below:

• Download Link 1
• Download Link 2