inherited就是调用祖先类的函数,如果不带参数就是默认调用同名函数 如果带参数则表明子类中的函数个数可能比祖先类要多取其中的几个参数传过去 例如 祖先类有个函数 Create(AName:string); 子类有个函数 Create(AName:string;AComponent:TObject);override; 那么子类的Create函数内就可以这样调用祖先类: procedure TAClass.Create(AName:string;AComponent:TObject); begin Inherited Create(AName); end;
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Example code : Examples of Inherited with and without explicit parent method names |
// Full Unit code. // ----------------------------------------------------------- // You must store this code in a unit called Unit1 with a form // called Form1 that has an OnCreate event called FormCreate. unit Unit1; interface uses Forms, Dialogs, Classes, Controls, StdCtrls; type // Define a parent class, base on TObject by default TFruit = class public name : string; Constructor Create; overload; // This constructor uses defaults Constructor Create(name : string); overload; end; // Define a descendant types TApple = class(TFruit) public diameter : Integer; published Constructor Create(name : string; diameter : Integer); end; // The class for the form used by this unit TForm1 = class(TForm) procedure FormCreate(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} // Include form definitions // Create a fruit object - parameterless version constructor TFruit.Create; begin // Execute the parent (TObject) constructor first Inherited; // Call the parent Create method // Now set a default fruit name self.name := 'Fruit'; end; // Create a fruit object - parameterised version constructor TFruit.Create(name: string); begin // Execute the parent constructor first Inherited Create; // Call the parent Create method // And save the fruit name self.name := name; end; // Create an apple object constructor TApple.Create(name: string; diameter : Integer); begin // Execute the parent (TFruit) constructor first Inherited Create(name); // Call the parent method // Now save the passed apple diameter self.diameter := diameter; end; // Main line code procedure TForm1.FormCreate(Sender: TObject); var fruit : TFruit; banana : TFruit; apple : TApple; begin // Create 3 different fruit objects fruit := TFruit.Create; banana := TFruit.Create('Banana'); apple := TApple.Create('Pink Lady', 12); // See which of our objects are fruits if fruit Is TFruit then ShowMessage(fruit.name +' is a fruit'); if banana Is TFruit then ShowMessage(banana.name +' is a fruit'); if apple Is TFruit then ShowMessage(apple.name +' is a fruit'); // See which objects are apples if fruit Is TApple then ShowMessage(fruit.name +' is an apple'); if banana Is TApple then ShowMessage(banana.name +' is an apple'); if apple Is TApple then ShowMessage(apple.name +' is an apple'); end; end. |
Fruit is a fruit Banana is a fruit Pink Lady is a fruit Pink Lady is an apple |