On Tue, Aug 20, 2013 at 2:34 AM, Xiangrong Fang <xrf...@gmail.com> wrote: > Hi Flavio, > > Your findings confirmed mine, but not telling me why?
I don't know why, maybe FPC used to be more strict about the use of inherited, or the docs are simply wrong. > It seems that the "virtual" keyword has no use at all! It does, and the documentation is correct in this respect. > To confirm this, I just removed the > "inherited" call in TDerived, then re-run the program with or without > "virtual/override", the result is exactly same, i.e. with c2 (declared as > TBase), the following statements ALWAYS calls constructor of TDerived, NOT > TBase: > > c2 := TDerived.Create; > c2 := TBase(TDerived.Create); As I said - or tried to say ;) - in the other post, there won't be a difference when invoking the constructor on a "class literal" directly. The second line will generate the exact same code as the first one; you're instantiating a TDerived instance then "upcasting" it to TBase. > This is not same as the description in: > http://www.freepascal.org/docs-html/ref/refsu26.html Note this page is about methods and you're using constructors in your example. I would recommend you first do your tests on method declarations, and later learn about class references (i.e. "class of" declarations) and constructors. > BTW, the above documents are talking about objects, but I am using classes, > is there any difference here? > > Shannon AFAIU per the first page you sent, you can't shadow/reintroduce a virtual method in an object; when you redeclare a virtual method it overrides the base one. -Flávio _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
