Re: SPI-header-files safe for C++-compiler

From: "Marko Kreen" <markokr(at)gmail(dot)com>
To: "Jacob Rief" <jacob(dot)rief(at)gmx(dot)at>
Cc: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, neilc(at)samurai(dot)com, pgsql-patches(at)postgresql(dot)org, andrew(at)dunslane(dot)net
Subject: Re: SPI-header-files safe for C++-compiler
Date: 2007-06-29 10:02:26
Message-ID: e51f66da0706290302w2bbea43ds1820ce8f6541297d@mail.gmail.com
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On 6/29/07, Jacob Rief <jacob(dot)rief(at)gmx(dot)at> wrote:
> On Thu, 2007-28-06 at 01:15 -0400, Tom Lane wrote:
> > Sure, but we don't break them just on a whim. The bottom line here is
> > whether we are going to make a real commitment to making C++ usable as
> > a backend extension language --- and for the reasons I mentioned, that
> > would entail a lot more than renaming a few identifiers. It was already
> > pointed out upthread that wrapping the inclusions in extern "C" {...}
> > would fix the identifier part of the problem from the user side, so I do
>
> No, wrong. Adding extern "C" does not fix the C++-keywords as identifiers
> problem. Adding extern "C" only tells the compiler to switch off
> name-mangling. A C++-compiler does not allow any kind of plain-old C in
> such blocks. With some drawbacks, it is even perfectly legal to use some
> C++ features inside an extern "C" block.

I think you are better off wrpapping your C++ code to small
pure-C module and export only that to Postgres-interfacing
C code. Thus you keep away making C++ seeing Postgres code.

It is really a mistake to think C as subset of C++. They are
really different languages. C-as-subset-of-C++ works only
with trivial C code. If you have big, old, real-life codebase
like Postgres, it really does not pay off to force it to comply
with C++ rules. Just to avoid the work of writing intermediate
wrapper code.

--
marko

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