On Sat, 29 May 2010 16:54:44 -0700 Andrew Hall <andrew.h...@shaw.ca> wrote:
> On 29 May 10, at 15:26 , spir ☣ wrote: > > I cannot do that. C0 (and all classes) instances need a text method. I also > > cannot have 2 methods (one static, one virtual) with different names. It's > > a basic feature, always called with the same name. Like getItem for a > > hierarchy of collections: every collection must have it, and always under > > the same name, so that any client can rely on it. > > David is not suggesting you have two methods with different names - his > example is demonstrating the different behaviour of static and virtual > methods. Calling a static method is determined at compile time - the compiler > must use the actual class of your variable (or cast) - so your descendent > methods will never be called. This is what is happening to you at the moment > - only your base class Text method is called. Calling a virtual method is > determined at runtime based upon the actual class held by the variable (cast) > - it seems this is exactly what you need. Set your base class Text method as > virtual, and each descendent class Text method as override - your code should > then function as you require... > > element := C(list[index]); > text := element.text; > > if the pointer in list[index] is C1, C1.Text will be called. > > Regards, > Andrew. Thank you very much, David & Andre. Sorry, David, I had not understood the intent of your example post. Your comment and Andre's clarified everything. OK, I lurred myself by taking words too literally. I thought "virtual" meant unimplemented, to be implemented in sub-classes. So, for me, this could not apply to my case, since supaer-classes also need the method to be implemented. Just did a fast trial: works fine. Denis ________________________________ vit esse estrany ☣ spir.wikidot.com _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
