Article View: comp.sw.components
Article #129Re: Assignment in Ada
From: William Thomas Wolfe, 2847
Date: Sat, 23 Sep 1989 21:13
Date: Sat, 23 Sep 1989 21:13
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From ted@nmsu.edu (Ted Dunning):
> but where does this leave ada? no overloading or forbidding
> assignment leaves the writer of a reliable reference counting adt in a
> real pickle.
The fact that it is not possible in Ada 83 to overload ":=" has
not posed practical difficulties, since it is standard practice
to simply require the generic parameter structure
with procedure Assign (Target : in out Object_Type;
Source : in Object_Type) is <>;
thus substituting "Assign" for ":=" in a straightforward way.
There remains a technical problem in that we can't use "Assign"
to initialize variables at the moment of creation, which is probably
why this is one of the more popular Ada 9X revision requests.
I wouldn't use either form of assignment to do a reference-counting
system, though... it's too easy to create unkillable garbage if one
process dies while still holding claim to a reference.
Bill Wolfe, wtwolfe@hubcap.clemson.edu
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!ginosko!gem.mps.ohio-state.edu!wuarchive!mailrus!ncar!gatech!hubcap!billwolf%hazel.cs.clemson.edu From: billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu (William Thomas Wolfe, 2847 ) Newsgroups: comp.sw.components Subject: Re: Assignment in Ada Message-ID: <6556@hubcap.clemson.edu> Date: 23 Sep 89 21:13:43 GMT References: <TED.89Sep22225829@kythera.nmsu.edu> Sender: news@hubcap.clemson.edu Reply-To: billwolf%hazel.cs.clemson.edu@hubcap.clemson.edu Lines: 24