我有一个界面.
type IProgressObserver = interface(IInterface)
procedure ReportProgress(Progress:Integer);
procedure ReportError(Message:string);
end;
我使用命名类实现了接口,如下所示：
type TProgressObserver=class(TInterfacedobject,IProgressObserver)
procedure ReportProgress(Progress:Integer);
procedure ReportError(Message:string);
end;
... implementation of methods go here .....
addProgressObserver(TProgressObserver.Create);
是否可以在不声明类的情况下创建此接口的实例？像这个(虚构的)代码,它会做与上面相同的事情：
addProgressObserver(IProgressObserver.Create()
begin
procedure ReportProgress(Progress:Integer)
begin
ShowMessage('Progress Observed!');
end
procedure ReportError(Message:string)
begin
Log(Message);
end
end;);
Delphi有匿名程序,但是它有匿名类吗？
我找到了this similar question,但它是用Java编写的.
我正在使用Delphi 2010
解决方法
你可以匿名,使用匿名方法实现接口.但是你没有得到实际的编译器支持,你必须自己声明所有的匿名方法类型,然后实现实际的“匿名”类.给定您的IProgressObserver接口,实现看起来像这样：
type
// This is the interface we'll be dealing with.
IProgressObserver = interface(IInterface)
procedure ReportProgress(Progress:Integer);
procedure ReportError(Message:string);
end;
// This will help us anonymously create implementations of the IProgressObserver
// interface.
TAnonymousObserverImp = class(TInterfacedobject,IProgressObserver)
type
// Declare reference types for all the methods the interface needs.
TReportProgressproc = reference to procedure(Progress:Integer);
TReportErrorProc = reference to procedure(Message:string);
strict private
FReportProgressproc: TReportProgressproc;
FReportErrorProc: TReportErrorProc;
// Actual implementation of interface methods.
procedure ReportProgress(Progress:Integer);
procedure ReportError(Message:string);
// private constructor,so we'll forced to use the public "Construct" function
constructor Create(aReportProgressproc: TReportProgressproc; aReportErrorProc: TReportErrorProc);
public
// This takes the required anonymous methods as parameters and constructs an anonymous implementation
// of the IProgressObserver interface.
class function Construct(aReportProgressproc: TReportProgressproc; aReportErrorProc: TReportErrorProc): IProgressObserver;
end;
{ TAnonymousObserverImp }
class function TAnonymousObserverImp.Construct(
aReportProgressproc: TReportProgressproc;
aReportErrorProc: TReportErrorProc): IProgressObserver;
begin
// Call the private constructor
Result := TAnonymousObserverImp.Create(aReportProgressproc,aReportErrorProc);
end;
constructor TAnonymousObserverImp.Create(
aReportProgressproc: TReportProgressproc; aReportErrorProc: TReportErrorProc);
begin
inherited Create;
// We simply save the references for later use
FReportProgressproc := aReportProgressproc;
FReportErrorProc := aReportErrorProc;
end;
procedure TAnonymousObserverImp.ReportError(Message: string);
begin
// Delegate to anonymous method
FReportErrorProc(Message);
end;
procedure TAnonymousObserverImp.ReportProgress(Progress: Integer);
begin
// Delegate to anonymous method
FReportProgressproc(Progress);
end;
一旦完成所有代码,您就可以编写如下代码：
var i: IProgressObserver;
begin
i := TAnonymousObserverImp.Construct(
procedure (Progress:Integer)
begin
// Do something with Progress
end,procedure (Message:string)
begin
// Do something with Message
end
)
end;
对我来说看起来很匿名！鉴于在Delphi中实现匿名方法,它也相当快速有效.