[fpc-devel] {$Interfaces Corba} and TInterfacedObject

[Vincent Snijders]

Sergei Gorelkin schreef:
> Graeme Geldenhuys wrote:
>>
>> Beats me, I thought that might be needed for querying a object for
>> interfaces it supports...  As far as CORBA is concerned, I'm just
>> shooting in the dark here...  Information on CORBA usage is limited
>> and I can't find any FPC code examples to give me hints.  It seems
>> quite useless having the Corba support in FPC, if everything related
>> to Interfaces requires COM methods.
>>
> Think of Corba-styled interfaces as about "interfaces without COM glue", 
> not just as about "interfaces without refcounting". To get runtime 
> typecasting features, you have to implement it yourself. OTOH, you are 
> free to implement anything you want.
> 
> As for non-refcounted interfaced base class, you may want to use 
> TComponent. Of course, it has some overhead compared with 
> TInterfacedObject, but its features are quite useful in almost every 
> application.

Given:
type
   TAddCommand = class(TBaseCommnad, ICommand)
   <bla>
   end;

Does the compiler store somewhere that that TAddCommand implements ICommand? I 
assume it does the compile time check that TAddCommand implements all ICommands 
methods, but is there something similar provided by the compiler (or RTTI) which can 
be used to do something like
   ACommnd := TAddCommand.Create;
   if (ACommand is TBaseCommand) then
     writeln('This works');
   if (ACommand.InheritsFrom('TBaseCommand') then
     writeln('This works');
   if (ACommand is ICommand) then
     writeln('I don't know if this works, but I would expect it if you consider 
interfaces similar to abstract base classes');
   if (ACommand.Implements(ICommand)) then
     writeln('I don't know if this works, but it is similar to the InheritsFrom case');

Vincent