From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,87077e61d6b3095b X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-12-22 14:02:07 PST Path: archiver1.google.com!news2.google.com!news.maxwell.syr.edu!in.100proofnews.com!tdsnet-transit!newspeer.tds.net!sn-xit-02!sn-xit-01!sn-post-02!sn-post-01!supernews.com!corp.supernews.com!not-for-mail From: cl1motorsports Newsgroups: comp.lang.ada Subject: Re: how do i implement double-dispatching? Date: Mon, 22 Dec 2003 16:41:52 -0500 Organization: Posted via Supernews, http://www.supernews.com Message-Id: User-Agent: Pan/0.14.2 (This is not a psychotic episode. It's a cleansing moment of clarity. (Debian GNU/Linux)) References: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@supernews.com Xref: archiver1.google.com comp.lang.ada:3715 Date: 2003-12-22T16:41:52-05:00 List-Id: > thanks for all of your suggestions. after careful consideration i decided > to change the above Accept_Visitor procedure to: > > procedure Accept_Vistor(V:in out Visitor_Record'Class; Node : in Parse_Tree_Node_Record'Class) is > begin > if Node in Equal_Op'Class then > Visit(V, Equal_Op(Node)); > elsif Node in Number_Node'Class then > Visit(V, Number_Node(Node)); > ... > end if; > end Accept_Visitor; > > now it only dynamically dispatches on the Visitor_Record'Class and the > Node parameter is determined at compile time. I don't think i would have > figured that out by myself (at least not at this point in time). Okay. now it works when the Visitor type, Visit() procedures and the Accept_Visitor() procedure is in a separate package from the parse tree. but when i try to combine the 2 into one package i get an error about multiple dispatching on all of the Visit() procedures. what is my scope issue with being in the same package that doesn't apply to them being in 2 packages? Charles