Delphi Prism Custom Routines

In Prism, everything is within a class (just like with C#, VB.Net, and Java). So you create class methods using the method keyword. Alternatively, you can use procedure or function if you want the compiler to enforce returning or not returning a value.

[function/procedure] RoutineName : ReturnType; 

As with C++, your custom routine must come before it's first usage or you have to prototype it in the Interface section.

Old School: Delphi for .Net Step-by-Step Example

In this old-school Delphi for .Net example (before Delphi Prism), notice that you can use global functions and procedures. This was changed with Prism where everything is within a class.

1. Add SysUtils to the uses clause so we can use the VCL.Net IntToStr command.

interface

uses
  System.Drawing, System.Collections, System.ComponentModel,
  System.Windows.Forms, System.Data, Borland.Vcl.SysUtils;

2. Also in the interface section, prototype our two custom routines.

type
  //...default form class code here.

procedure SayHello(pName: String);
function Add(a, b : Integer) : integer;

3. Add the two custom routines to the implementation section.

implementation

//...Delphi generated code here.

procedure SayHello(pName: String);
begin
  MessageBox.Show('Hello ' + pName);
end;

function Add(a, b : Integer) : integer;
begin
  result := a + b;
end;

end.

4. Call the two custom routines from a button click event:

procedure TWinForm.Button2_Click(sender: System.Object; e: System.EventArgs);
begin
  SayHello('Mike');
  MessageBox.Show(IntToStr(Add(3, 4)));
end;