Tutorial-supports determine if the interface (Instance) is supported

1 functionTcommandenabledcontroller.getcommandvisible (ConstAcommandname:string): Boolean;2 var3 I:integer;4   //Defining Interface Recipients5 Ocommandvisibleexecutor:icommandvisibleexecutor;6 begin7Result: =True;8    forI: =0  toFexecutors.count-1  Do9   beginTen     //determine if the interface supports One     ifSupports (Fexecutors[i], icommandvisibleexecutor, Ocommandvisibleexecutor) Then A     begin -       //using the interface recipient -       if  notOcommandvisibleexecutor.commandvisible (Acommandname) Then the       begin -Result: =False; - Break ; -       End; +     End; -   End; + End;

The function supports in Delphi is located in the Sysutils unit

Defined as follows:

1 {Interface Support Routines}2 3 functionSupports (ConstInstance:iinterface;ConstIid:tguid; outIntf): Boolean;Overload;4 functionSupports (ConstInstance:tobject;ConstIid:tguid; outIntf): Boolean;Overload;5 functionSupports (ConstInstance:iinterface;ConstIID:TGUID): Boolean;Overload;6 functionSupports (ConstInstance:tobject;ConstIID:TGUID): Boolean;Overload;7 functionSupports (ConstAclass:tclass;ConstIID:TGUID): Boolean;Overload;

The implementation is as follows :

1 {Interface Support Routines}2 3 functionSupports (ConstInstance:iinterface;ConstIid:tguid; outIntf): Boolean;4 begin5Result: = (Instance <>Nil) and(Instance.queryinterface (IID, Intf) =0);6 End;7 8 functionSupports (ConstInstance:tobject;ConstIid:tguid; outIntf): Boolean;9 varTen Lunknown:iunknown; One begin AResult: = (Instance <>Nil) and -(Instance.getinterface (IUnknown, Lunknown) andSupports (Lunknown, IID, Intf))or - instance.getinterface (IID, Intf)); the End; -  - functionSupports (ConstInstance:iinterface;Constiid:tguid): Boolean; - var + Temp:iinterface; - begin +Result: =Supports (Instance, IID, Temp); A End; at  - functionSupports (ConstInstance:tobject;Constiid:tguid): Boolean; - var - Temp:iinterface; - begin -Result: =Supports (Instance, IID, Temp); in End; -  to functionSupports (ConstAclass:tclass;Constiid:tguid): Boolean; + begin -Result: = Aclass.getinterfaceentry (IID) <>Nil; the End;

Tutorial-supports determine if the interface (Instance) is supported