> I used RTTI to avoid defining an additional constant array of > strings to have a unit output debug information for > enumerated types. Otherwise I never did see any use of this. > > Could you give a real world example ?
Do you want a real world example for what better RTTI in general is useful? Or custom attributes specifically? For just one of many examples for attributes, just have a look here: http://msdn2.microsoft.com/en-us/library/Aa480190.aspx You don't need to read all of it, just search for "[" and have a look at the code snippets. Yes, sure there are other ways how you could possibly provide that information. But custom attributes provide a simple and generic mechanism to associate runtime dicoverable information with specific types/members of type. As for better runtime information in general, one example of what I've done myself in Delphi using Interface RTTI (which as I mentioned in another post is unfortunately rather limited) is something like this: function CreateInvokeWrapper(const aInterface : InxInterface; const aInterceptor : InxInvokeInterceptor; out aWrappedIntf : InxInterface) : HRESULT; InxInvokeInterceptor = interface(InxInterface) ['{7DC415F5-B252-457E-A57C-393CD326275C}'] function InterceptInvoke(aMethod : PnxIntfMethEntry; aParams : PnxPointerArray; const aCallFrame : InxCallFrame) : HRESULT; end; InxCallFrame = interface(InxInterface) ['{6DABF6D0-4419-4074-9CF4-75145AC8A34B}'] function CopyFrom(aParams : PnxPointerArray) : HRESULT; function MakeCall: HRESULT; end; You call CreateInvokeWrapper, passing in an existing interface and a reference to an interceptor class you implement and get back a new interface. You can call QueryInterface on that new interface as required to get other interfaces implemented by the class of the interface you originally passed in. Any call on a method of any of these wrapped interfaces ends up in a call to InterceptInvoke where you aMethod gives you exact information which interface, which method, how many params, param and result types... aParams then gives you access to the params and result which allows you to inspect and/or change them. If you want to forward the call (with possibly changed parameter values) to the inner interface you can call aCallFrame.MakeCall (but you don't have to) and can then inspect and/or change the params (might be var and out params among them) and result before returning. Naturally, if I can do that I can also do the 2 half (proxy/stub) in isolation on different machines which I'm using to implement a remoting framework: http://nexusdbng.blogspot.com/2007/09/remoting-introduction.html Cheers, Thorsten _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
