Re: Object Oriented Compiler Design Problem

On 5 Sep 1998 01:20:58 -0400, mayurnaik@my-dejanews.com wrote:
[OO compiler stuff snipped]
>
>The function symbol* add(symbol*, symbol*) cannot be made a virtual function
>of class symbol, since it is a friend function. But, the moment it is a
>friend function, it does not know whether the symbols to be added are
>Constants or Variables


This is a classic case of the need for double-dispatch (choosing a
function based on two types instead of one). A modern approach would
be based on the Visitor pattern. I would take this up at the
comp.object newsgroup or on the OTUG mailing list (go to www.oma.com
to sign up for that). (I'm afraid I don't have much more to offer on
the subject; I'm posting to ensure that these ideas are at least
mentioned.)


>[I suspect a union with a type field is it. RTTI in this case would amount to
>the same thing. -John]


I'm certain that RTTI is not necessary.
--

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