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   ► KBProgrammingDelphi for W...Language Det...   Print This    All Groups  
  From the January 2010 Issue of Prestwood eMag
 
Delphi Language Details:
Delphi Custom Routines (procedure, function)
 
Posted 12 years ago on 11/11/2008 and updated 12/25/2008
Delphi Code Snippet:
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KB101600

Languages Focus: Custom Routines

For non-OOP languages, a custom routine is a function, procedure, or subroutine and for pure OOP languages, a custom routine is a class method. Hybrid languages (both non-OOP and OOP) combine both.

Delphi Custom Routines

Delphi is a hybrid language so you can create either class methods (functions and procedures) or you can create global functions and procedures. When a function or procedure is part of a class, it is a class method.

[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.

Note: Contrast Delphi with Delphi Prism which is an OOP language (everything is within a class). Both Delphi and Delphi Prism are based on Object Pascal but implement OOP features differently and have some syntax differences too.

Syntax Example:
procedure SayHello(pName: String);
begin
  ShowMessage('Hello ' + pName);
end;
 
function Add(p1, p2 : Double): Double;
begin
  Result := p1 + p2;
end;

The following code from a button click event calls the two routines:

procedure TForm2.CustRClick(Sender: TObject);
begin
  SayHello('Mike');
  ShowMessage('2+2=' + FloatToStr(Add(2,2)));
end;

More Info


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