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From: ncohen@watson.ibm.com (Norman H. Cohen)
Subject: Re: Factory Pattern in Ada
Date: 1996/08/25
Message-ID: <4vq8so$10a6@watnews1.watson.ibm.com>#1/1
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distribution: world
references: <321E17F6.167E@velveeta.apdev.cs.mci.com>
organization: IBM T.J. Watson Research Center
reply-to: ncohen@watson.ibm.com
newsgroups: comp.lang.ada
Date: 1996-08-25T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <321E17F6.167E@velveeta.apdev.cs.mci.com>, James_Rogers
<jrogers@velveeta.apdev.cs.mci.com> writes: 

|> Since Binary_Node is a descendant of Node, why does the compiler
|> complain about the assignment of a value of Binar_Node_Access to
|> a type of Node_Access (as defined above)?

Conversion from access-to-derived-type to access-to-parent-type is
allowed, but only if the access-to-parent type is a general
("access all") access type.  Even then, the conversion must be written as
an explicit type conversion.

--
Norman H. Cohen    ncohen@watson.ibm.com