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
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