Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!samsung!rex!wuarchive!usc!elroy.jpl.nasa.gov!ncar!boulder!uswat!csn!tigger!streich
From: streich@tigger.Colorado.EDU (Mark Streich)
Newsgroups: comp.lang.pascal
Subject: Re: TP5.5: Can't store method in procedure variable
Keywords: Method Object Procedure TP5.5
Message-ID: <1990Dec7.153019.23716@csn.org>
Date: 7 Dec 90 15:30:19 GMT
References: <1990Dec3.061013.22258@ux1.cso.uiuc.edu> <1990Dec4.232438.927@ux1.cso.uiuc.edu> <1990Dec6.143527.21330@watserv1.waterloo.edu>
Sender: streich@tigger.colorado.edu
Followup-To: comp.lang.pascal
Distribution: na
Organization: University of Colorado, Boulder
Lines: 34
Nntp-Posting-Host: tigger.colorado.edu

dmurdoch@watserv1.waterloo.edu (D.J. Murdoch - Statistics) writes:
>You seem to be allowed to do it [get address of object method] if you 
>specify the method with a type prefix, but not with a variable prefix.  
>For example:
>
>type
>  myobj = object
>    constructor init;
>    procedure static;
>    procedure virt; virtual;
>  end;
>{  code for init, static, and virt omitted... }
>
>var
>  o : myobj;
>  p : pointer;
>begin
>  p := @myobj.static; { these first two work }
>  p := @myobj.virt;
>  o.init;
>  p := @o.static;     { these last two don't compile }
>  p := @o.virt;
>end.

This looks quite suspicious because you're taking the address of a class,
and not the address of an *instance* of the class.  Two instances may 
(obviously?) have different virtual methods.  As a comparison, it looks
like you're taking the address of the integer type rather than an integer
variable. (i.e.,  p := @integer   rather than  p := @i { of type integer })

Does this run correctly with different instances of the object?

Mark Streich
streich@tigger.colorado.edu