Re: C++ Headers

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: C++ Headers
Date: 2001-05-23 15:35:31
Message-ID: 200105231535.f4NFZVN08207@candle.pha.pa.us
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> > > > We have added more const-ness to libpq++ for 7.2.
> > >
> > > Breaking link compatibility without bumping the major version number
> > > on the library seems to me serious no-no.
> > >
> > > To const-ify member functions without breaking link compatibility,
> > > you have to add another, overloaded member that is const, and turn
> > > the non-const function into a wrapper. For example:
> > >
> > > void Foo::bar() { ... } // existing interface
> > >
> > > becomes
> > >
> > > void Foo::bar() { ((const Foo*)this)->bar(); }
> > > void Foo::bar() const { ... }
> >
> > Thanks. That was my problem, not knowing when I break link compatiblity
> > in C++. Major updated.
>
> Wouldn't it be better to add the forwarding function and keep
> the same major number? It's quite disruptive to change the
> major number for what are really very minor changes. Otherwise
> you accumulate lots of near-copies of almost-identical libraries
> to be able to run old binaries.
>
> A major-number bump should usually be something planned for
> and scheduled.

That const was just one of many const's added, and I am sure there will
be more stuff happening to C++. I changed a function returning short
for tuple length to int. Not worth mucking it up.

If it was just that one it would be OK.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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