D7以來的變化
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Language and Compiler Features Since Delphi 7
Inlining Routines can now be marked with theinline
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
TMyClass =Class Helpersclass
class
operator Add(a, b: TMyClass): TMyClass;// Addition of two operands of type TMyClass
class
operator Subtract(a, b: TMyClass): TMyclass;// Subtraction of type TMyClass
class
operator Implicit(a: Integer): TMyClass;// Implicit conversion of an Integer to type TMyClass
class
operator Implicit(a: TMyClass): Integer;// Implicit conversion of TMyClass to Integer
class
operator Explicit(a: Double): TMyClass;// Explicit conversion of a Double to TMyClass
end
;// Example implementation of Add class operator
TMyClass.Add(a, b: TMyClass): TMyClass;begin
...end
;var
x, y: TMyClassbegin x := 12;// Implicit conversion from an Integer
y := x + x;// Calls TMyClass.Add(a, b: TMyClass): TMyClass
b := b + 100;// Calls TMyClass.Add(b, TMyClass.Implicit(100))
end
;
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.
strict private Thetype
TMyClass =class
procedure
MyProc;function
MyFunc: Integer;end
; ...procedure
TMyClass.MyProc;var
X: Integer;begin
X := MyFunc;end
;function
TMyClass.MyFunc: Integer;begin
...end
;...type
TMyClassHelper =class
helperfor
TMyClassprocedure
HelloWorld;function
MyFunc: Integer;end
; ...procedure
TMyClassHelper.HelloWorld;begin
WriteLn(Self.ClassName);// Self refers to TMyClass type, not TMyClassHelper
end
;function
TMyClassHelper.MyFunc: Integer;begin
...end
;...var
X: TMyClass;begin
X := TMyClass.Create; X.MyProc;// Calls TMyClass.MyProc
X.HelloWorld;// Calls TMyClassHelper.HelloWorld
X.MyFunc;// Calls TMyClassHelper.MyFunc
end
;
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 protected
creates 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 abstracttype
TMyRecord =record
type
TInnerColorType = Integer;var
Red: Integer;class
var
Blue: Integer;procedure
printRed();constructor
Create(val: Integer);property
RedProperty: TInnerColorTyperead
Redwrite
Red;class
property
BlueProp: TInnerColorTyperead
Bluewrite
Blue;end
;constructor
TMyRecord.Create(val: Integer);begin
Red := val;end
;procedure
TMyRecord.printRed;begin
writeln('Red: '
, Red);end
;
Classes, and not just methods, can be declared as abstract.
class sealed Classes marked as sealed cannot be inherited from.type
TAbstractClass =class
abstract
procedure
SomeProcedure;end
;
class const Classes can now have class constants -- a constant value associated with the class itself and not an instance of the class.type
TAbstractClass =class
sealedprocedure
SomeProcedure;end
;
class type A class can now contain a type declaration that is usable only within that class.type
TClassWithConstant =class
public
const
SomeConst ='This is a class constant'
;end
;procedure
TForm1.FormCreate(Sender: TObject);begin
ShowMessage(TClassWithConstant.SomeConst);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.type
TClassWithClassType =class
private
type
TRecordWithinAClass =record
SomeField:string
;end
;public
class
var
RecordWithinAClass: TRecordWithinAClass;end
; ...procedure
TForm1.FormCreate(Sender: TObject);begin
TClassWithClassType.RecordWithinAClass.SomeField :='This is a field of a class type declaration'
; ShowMessage(TClassWithClassType.RecordWithinAClass.SomeField);end
;
final methods A virtual method that you override can now be marked final, preventing derived classes from overriding that method.type
TOuterClass =class
strictprivate
MyField: Integer;public
type
TInnerClass =class
public
MyInnerField: Integer;procedure
InnerProc;end
;procedure
OuterProc;end
;procedure
TOuterClass.TInnerClass.InnerProc;begin
...end
;
TAbstractClass = classabstractsealed methods Classes marked aspublic
procedure
Bar;virtual
;end
; TSealedClass = classsealed(TAbstractClass)public
procedure
Bar;override
;end
; TFinalMethodClass =class
(TAbstractClass)public
procedure
Bar;override
;final
;end
;
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.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:type
TMyClass =class
strictprivate
class
var
FX: Integer; strictprotected
// Note: accessors for class properties must be declared class static.
class
function
GetX: Integer;static
;class
procedure
SetX(val: Integer);static
;public
class
property
X: Integerread
GetXwrite
SetX;class
procedure
StatProc(s:String
);static
;end
;TMyClass.X := 17;TMyClass.StatProc('Hello'
);
for
Elementin
ArrayExprdo
Stmt;for
Elementin
StringExprdo
Stmt;for
Elementin
SetExprdo
Stmt;for
Elementin
CollectionExprdo
Stmt;
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