Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

{ 
  Delphi pruft die Typen der ubergebenen Variablen fur entsprechende 
  var Parameter einer Prozedure / Funtion anhand der gefuhrten Typen. 
  Dabei wird unterschieden zwischen strenge und schwache Typendeklarationen. 
  Das kann man ausnutzen, um bestimmte Bedingungen zu kreieren, die 
  beim Programmieren respektiert sein mussen: Delphi wird u.U. einen 
  Compiler-Fehler produzieren. 
}

 { 
  Delphi checks the type of variables you pass in a procedure or a function 
  call for declared var parameters. 
  It makes a difference if you make a strong or weak type declaration. 
  You can use this casuality to create a design time proofing rule, proofing 
  the code at design time. Delphi won't compile a code part if it's 
  "strong checked". 
}

 type
   // Strenge Prufung wird veranlasst 
  // Strong checking will be operated 
  TCheckedIniFileNameType = type
      string;

   // Schwache Prufung bei dieser Typ-Deklaration 
  // Weak checking for this type declaration 
  TSimpleIniFileNameType = string;

   { This will be strong checked }
 procedure CheckedTypeProcedure(var IniFileName: TCheckedIniFileNameType);
 begin
   ShowMessage(IniFileName);
 end;

 { This will be less strong checked }
 procedure SimpleTypeProcedure(var IniFileName: TSimpleIniFileNameType);
 begin
   ShowMessage(IniFileName);
 end;

 { Weakest form of checking }
 procedure NoTypeProcedure(var IniFileName: string);
 begin
   ShowMessage(IniFileName);
 end;

 procedure TForm4.Button1Click(Sender: TObject);
 var
   StringOnly: string;
   SimpleIniFileName: TSimpleIniFileNameType;
   CheckedIniFileName: TCheckedIniFileNameType;
 begin
   StringOnly         := 'C:\TEST.TXT';
   SimpleIniFileName  := 'C:\TEST.TXT';
   CheckedIniFileName := 'C:\TEST.TXT';

   // This will compile... 
  CheckedTypeProcedure(CheckedIniFileName);
   SimpleTypeProcedure(SimpleIniFileName);
   SimpleTypeProcedure(StringOnly);
   NoTypeProcedure(StringOnly);
   NoTypeProcedure(SimpleIniFileName);

   // This will not... 
  CheckedTypeProcedure(SimpleIniFileName);
   CheckedTypeProcedure(StringOnly);
   SimpleTypeProcedure(CheckedIniFileName);
   NoTypeProcedure(CheckedIniFileName);
 end;