Re: [boost] [Booster] Or boost is useless for library developers

Subject: Re: [boost] [Booster] Or boost is useless for library developers
From: Dean Michael Berris (mikhailberis_at_[hidden])
Date: 2010-05-19 16:49:57

On Wed, May 19, 2010 at 1:02 PM, Gennadiy Rozental <rogeeff_at_[hidden]> wrote:
> Dean Michael Berris <mikhailberis <at> gmail.com> writes:
>
>> Putting everything in headers lets me, the library writer
>> to never ever have to worry about preserving ABI because, well,
>> there's no ABI to preserve across releases.
>
> How having simple API with hidden implementation lead to ABI problems?
>

Well, because your return types might not be trivial and these
returned types may have to inherit from some other types that need to
be known and need to be preserved across version releases. Of course
that is a corner case that might be easily avoided if you only ever
returned int's or primitive data types.

And then you have to run into the cost of doing a pimpl, and/or the
cost of doing virtual function calls when they're really just
unnecessary. I'm not even talking about performance here, just the
pure necessity of it. If things can and should be done statically,
there is no good reason to introduce an additional pointer or a vtable
-- even if that reason is to preserve ABI compatibility, because in my
head that's not a valid reason.

And no, I don't think having pimpls all around will lead to ABI
problems -- but it is something that I would rather avoid with just
having a header-only library. Because as a library developer, I
*don't* want to deal with ABI issues and just be able to release
header-only libraries that just work without having to worry about
preserving compatibility with earlier releases.

But that might just be me. ;)

-- 
Dean Michael Berris
deanberris.com