[Gllug] open source centric ICT in Schools from Sept 2012 ?

[Nix]

On 13 Jan 2012, Alain Williams spake thusly:
> Not what I said. I said that open standards are more important than open source.
>
> An example of that is the definition of the Unix file system. This is an
> API: open/close/create/readdir/... How it is implemented is, at the application
> programming level of zero interest. This means that your application will
> work on very different file systems: sysv, ext2, reiser, ...

Well, not quite. POSIX doesn't specify 'the Unix file system' (that
would be BSD FFS perhaps), but rather the *programming interface* to the
filesystem. It doesn't quite specify it in enough detail, and most
implementations violate the definition in various small ways (certainly
Linux does, and NFS is a tissue of violations), but most implementations
are close enough for interoperable software to be written without too
much pain.

As far as I know Unix is unique in having something like POSIX as a
guiding standard, rather than a central implementation which everyone
must be bug-for-bug compatible with -- though there is some of that.
(Right now, everyone has to be bug-for-bug compatible with Linux. Back
in the day, it was Solaris, SunOS, perhaps even OSF/1...)

> Also: if you have a reference base in code then the temptation is to implement
> the same thing rather than something that is different and perhaps better in
> some way.

But if your only spec is the code, you can no longer distinguish between
bugs in the original implementation and features which must be
implemented. With a spec, your only problem arises when things that were
believed to be features turn out to be bugs. (The existence of seekdir()
/ telldir(), for instance. die die DIE DIE DIE *froth* sorry, my de-POSIX
pills are in the green container over there.)

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