Language and Compiler Features Since Delphi 7 |
| Inlining | Routines can now be marked with the inline directive. This tells the compiler that, instead of actually calling the routine, it should emit code that includes the routine at the call site. |
| Operator Overloading | Delphi allows certain functions, or operators, to be overloaded within record declarations class="sourcecode">
TMyClass = class="keyword">class
class="keyword">class operator Add(a, b: TMyClass): TMyClass; class="comment">// Addition of two operands of type TMyClass
class="keyword">class operator Subtract(a, b: TMyClass): TMyclass; class="comment">// Subtraction of type TMyClass
class="keyword">class operator Implicit(a: Integer): TMyClass; class="comment">// Implicit conversion of an Integer to type TMyClass
class="keyword">class operator Implicit(a: TMyClass): Integer; class="comment">// Implicit conversion of TMyClass to Integer
class="keyword">class operator Explicit(a: Double): TMyClass; class="comment">// Explicit conversion of a Double to TMyClass
class="keyword">end;
class="comment">// Example implementation of Add class operator
TMyClass.Add(a, b: TMyClass): TMyClass;
class="keyword">begin
...
class="keyword">end;
class="keyword">var
x, y: TMyClassbegin
x := 12; class="comment">// Implicit conversion from an Integer
y := x + x; class="comment">// Calls TMyClass.Add(a, b: TMyClass): TMyClass
b := b + 100; class="comment">// Calls TMyClass.Add(b, TMyClass.Implicit(100))
class="keyword">end;
|
| Class Helpers | A class helper is a type that - when associated with another class - introduces additional method names and properties which may be used in the context of the associated class (or its descendants). Class helpers are a way to extend a class without using inheritance. A class helper simply introduces a wider scope for the compiler to use when resolving identifiers. When you declare a class helper, you state the helper name, and the name of the class you are going to extend with the helper. You can use the class helper any place where you can legally use the extended class. The compiler's resolution scope then becomes the original class, plus the class helper. Class helpers provide a way to extend a class, but they should not be viewed as a design tool to be used when developing new code. They should be used solely for their intended purpose, which is language and platform RTL binding. class="sourcecode">class="keyword">type
TMyClass = class="keyword">class
class="keyword">procedure MyProc;
class="keyword">function MyFunc: Integer;
class="keyword">end;
...
class="keyword">procedure TMyClass.MyProc;
class="keyword">var
X: Integer;
class="keyword">begin
X := MyFunc;
class="keyword">end;
class="keyword">function TMyClass.MyFunc: Integer;
class="keyword">begin
...
class="keyword">end;
...
class="keyword">type
TMyClassHelper = class="keyword">class helper class="keyword">for TMyClass
class="keyword">procedure HelloWorld;
class="keyword">function MyFunc: Integer;
class="keyword">end;
...
class="keyword">procedure TMyClassHelper.HelloWorld;
class="keyword">begin
WriteLn(Self.ClassName); class="comment">// Self refers to TMyClass type, not TMyClassHelper
class="keyword">end;
class="keyword">function TMyClassHelper.MyFunc: Integer;
class="keyword">begin
...
class="keyword">end;
...
class="keyword">var
X: TMyClass;
class="keyword">begin
X := TMyClass.Create;
X.MyProc; class="comment">// Calls TMyClass.MyProc
X.HelloWorld; class="comment">// Calls TMyClassHelper.HelloWorld
X.MyFunc; class="comment">// Calls TMyClassHelper.MyFunc
class="keyword">end;
|
| strict private | The private keyword actually creates a " friendship" relationship between classes in the same unit. The strict private declaration creates a true private field, not viewable by any other class, not even classes in the same unit. |
| strict protected | Similar to the strict private declaration, strict protectedcreates a true protected member, visible only to the declaring class and its descendents. |
| Records with Methods | In addition to fields, records now may have properties and methods (including constructors), class properties, class methods, class fields, and nested types. class="sourcecode">class="keyword">type
TMyRecord = class="keyword">record
class="keyword">type
TInnerColorType = Integer;
class="keyword">var
Red: Integer;
class="keyword">class class="keyword">var
Blue: Integer;
class="keyword">procedure printRed();
class="keyword">constructor Create(val: Integer);
class="keyword">property RedProperty: TInnerColorType class="keyword">read Red class="keyword">write Red;
class="keyword">class class="keyword">property BlueProp: TInnerColorType class="keyword">read Blue class="keyword">write Blue;
class="keyword">end;
class="keyword">constructor TMyRecord.Create(val: Integer);
class="keyword">begin
Red := val;
class="keyword">end;
class="keyword">procedure TMyRecord.printRed;
class="keyword">begin
writeln(class="quote">'Red: ', Red);
class="keyword">end;
|
| class abstract | Classes, and not just methods, can be declared as abstract. class="sourcecode">class="keyword">type
TAbstractClass = class="keyword">class class="keyword">abstract
class="keyword">procedure SomeProcedure;
class="keyword">end;
|
| class sealed | Classes marked as sealed cannot be inherited from. class="sourcecode">class="keyword">type
TAbstractClass = class="keyword">class sealed
class="keyword">procedure SomeProcedure;
class="keyword">end;
|
| class const | Classes can now have class constants -- a constant value associated with the class itself and not an instance of the class. class="sourcecode">class="keyword">type
TClassWithConstant = class="keyword">class
class="keyword">public
class="keyword">const SomeConst = class="quote">'This is a class constant';
class="keyword">end;
class="keyword">procedure TForm1.FormCreate(Sender: TObject);
class="keyword">begin
ShowMessage(TClassWithConstant.SomeConst);
class="keyword">end;
|
| class type | A class can now contain a type declaration that is usable only within that class. class="sourcecode">
class="keyword">type
TClassWithClassType = class="keyword">class
class="keyword">private
class="keyword">type
TRecordWithinAClass = class="keyword">record
SomeField: class="keyword">string;
class="keyword">end;
class="keyword">public
class="keyword">class class="keyword">var
RecordWithinAClass: TRecordWithinAClass;
class="keyword">end;
...
class="keyword">procedure TForm1.FormCreate(Sender: TObject);
class="keyword">begin
TClassWithClassType.RecordWithinAClass.SomeField := class="quote">'This is a field of a class type declaration';
ShowMessage(TClassWithClassType.RecordWithinAClass.SomeField);
class="keyword">end;
|
| class var | A class can also have a class variable, applicable only to the class and not an instance of the class. See "class type" for an example. |
| class property | A class can have a class property, which is a property that applies only to the class reference and not to an instance of a class. The accessors for the class property must be either class methods or class variables. See the example in "static class methods" below. |
| nested classes | Type declarations can be nested within class declarations. They present a way to keep conceptually related types together, and to avoid name collisions. class="sourcecode">class="keyword">type
TOuterClass = class="keyword">class
strict class="keyword">private
MyField: Integer;
class="keyword">public
class="keyword">type
TInnerClass = class="keyword">class
class="keyword">public
MyInnerField: Integer;
class="keyword">procedure InnerProc;
class="keyword">end;
class="keyword">procedure OuterProc;
class="keyword">end;
class="keyword">procedure TOuterClass.TInnerClass.InnerProc;
class="keyword">begin
...
class="keyword">end;
|
| final methods | A virtual method that you override can now be marked final, preventing derived classes from overriding that method. class="sourcecode">TAbstractClass = classabstract
class="keyword">public
class="keyword">procedure Bar; class="keyword">virtual;
class="keyword">end;
TSealedClass = classsealed(TAbstractClass)
class="keyword">public
class="keyword">procedure Bar; class="keyword">override;
class="keyword">end;
TFinalMethodClass = class="keyword">class(TAbstractClass)
class="keyword">public
class="keyword">procedure Bar; class="keyword">override; class="keyword">final;
class="keyword">end;
|
| sealed methods | Classes marked as sealed cannot be descended from. See the example in 'final methods'. |
| static class methods | Classes can have static class methods -- i.e. methods that can be called from a class type. Class static methods can be accessed without an object reference. Unlike ordinary class methods, class static methods have no Self parameter at all. They also cannot access any instance members. (They still have access to class fields, class properties, and class methods.) Also unlike class methods, class static methods cannot be declared virtual. class="sourcecode">class="keyword">type
TMyClass = class="keyword">class
strict class="keyword">private
class="keyword">class class="keyword">var
FX: Integer;
strict class="keyword">protected
class="comment">// Note: accessors for class properties must be declared class static.
class="keyword">class class="keyword">function GetX: Integer; class="keyword">static;
class="keyword">class class="keyword">procedure SetX(val: Integer); class="keyword">static;
class="keyword">public
class="keyword">class class="keyword">property X: Integer class="keyword">read GetX class="keyword">write SetX;
class="keyword">class class="keyword">procedure StatProc(s: class="keyword">String); class="keyword">static;
class="keyword">end;
TMyClass.X := 17;
TMyClass.StatProc(class="quote">'Hello');
|
| for-in loop | Delphi 2007 for Win32 supports for-element-in-collection style iteration over containers. The following container iteration patterns are recognized by the compiler:
class="sourcecode"> class="keyword">for Element class="keyword">in ArrayExpr class="keyword">do Stmt;
class="keyword">for Element class="keyword">in StringExpr class="keyword">do Stmt;
class="keyword">for Element class="keyword">in SetExpr class="keyword">do Stmt;
class="keyword">for Element class="keyword">in CollectionExpr class="keyword">do Stmt;
|
