Re: encapsulating directory operations

"Paul Edwards" <mutazilah@gmail.com> writes:

"Keith Thompson" <Keith.S.Thompson+u@gmail.com> wrote in message
news:87tt5ezx9y.fsf@nosuchdomain.example.com...

"Paul Edwards" <mutazilah@gmail.com> writes:

"Keith Thompson" <Keith.S.Thompson+u@gmail.com> wrote in message
news:87a5770xjw.fsf@nosuchdomain.example.com...

"Paul Edwards" <mutazilah@gmail.com> writes:
[...]

So is it right to expect directories to be covered by C90?

>
Of course not.  C90 is frozen, defined by the ISO standard published
in 1990.  It is an obvious fact, that you cannot have missed,
that the C90 standard does not support operations on directories.
(Neither does any later ISO C standard.)
>
I'm guessing that you meant something by "expect" that differs from
its usual meaning.  Can you clarify?

>
When C90 was being written - or indeed - when K&R was
being written - if there hadn't been pressure to "bring to market",
would you EXPECT a language standard - any language
standard - but in this specific instance the ISO/IEC 9899:1990
committee - to have included a standard form of directory
manipulation?

>
Ah, that's a very different question.  I have no answer, because
I don't care.  C90 is what it is.  Of course it could have been different.

>
My question is not "could", it is "should", or "ideally".
>

As far as I know, there was never any LOGICAL barrier
to including basic directory manipulation in C90.

>
None that I can think of.

>
Ok, that's a great start. That answers one of my questions.
>

But it could potentially be even neater if it was hidden
away behind a standard fopen etc call.
>
That's my question.

>
Sure, it would be theoretically possible to treat directories as files,
and to make reading from a FILE* resulting from calling fopen() with a
directory name give you access to the directory entries.
>
I don't think it would be a particularly good idea.

>
Can you tell me why?

It artificially merges two very distinct concepts for no good
reason that I can see.  Operations that make sense for files make
far less sense for directories.  There's no shortage of interfaces
for dealing with directories (POSIX, C++, Perl, etc.), and I'm not
aware of any of them that conflate directories and files.  It's true
that "(almost) everything is a file" is part of the Unix philosophy,
and directories are typically stored as file-like objects with most
of the same attributes that files can have, but I can't think of
any good reason for higher level code to care about that.

Directory access is largely a solved problem.  If you insist on
creating yet another solution, I recommend following the existing
solutions.

...]

You may as well throw in the entire POSIX, the entire C23,
and the entire C++ into C90 too. There needs to be some
philosophy to set constraints.

So invent a philosophy that meets your requirements.

...]

C90 wasn't designed by one person. K&R C was more-or-less
designed by one person. But I don't want a language designed
by one person.
>
I want a language that is accepted by a committee.
>
Not the C99 committee. Not the C23 committee.
>
The C90+ committee. I would probably decide who gets
to sit on the committee though.

I would frankly be surprised if anyone other than you were willing
to be on that committee.  Remember that being a member of a language
standard committee is a lot of work, and is typically unpaid.

Richard would probably be on the committee, as he has
a shared goal. It's not likely that he wants to though, and
note that the committee doesn't formally exist yet. And
nor does it need to formally exist. It is enough to have
a discussion in comp.lang.c and when you, Keith, give
the go-ahead for directory manipulations to have been
incorporated into C90 - because you can't see anything
wrong with it - then the theoretical committee can
continue their work on directory manipulations in C90+.

Do not mistake my idle comment for an endorsement.

Plus you just said above that it would be reasonable for
the POSIX directory operations to be directly incorporated
into C90+'s "standard library".
>
The C90 people didn't choose to do that.
>
That doesn't necessarily constrain the C90+ people.

>
Right.
>

But it does beg the question - would it have been
ACCEPTABLE for the ANSI 89 people to have
put that directory manipulation stuff into the C89
standard IF they could do so quickly?

>
Yes.
>

Or would that be an ABOMINATION?

>
No.  (WTF??)

>
I don't understand your question.

If you don't know what "WTF" means, I suggest a web search.  I was
expression surprise that anyone would use a loaded word like
"abomination" for something so innocuous.

[...]

I have a series of questions that begin with:
>
If xyz had been added to the C90 standard, would you have
considered that to be odd/wrong? If so, why?

I'm unlikely to be interested in answering most of those questions.
I don't see how they're in any way relevent, even to what you're
working on.  I have no objection to a new language based on C90,
but agonizing about what the C90 committee should or should not
have done is IMHO a waste of time.

[...]

It hasn't been addressed. Nor has fpeek() in a previous thread.
Nor ESC_STR.

>
I don't remember what fpeek() is supposed to be;

>
See if a stream is known to have characters in it.

I'd need a more precise explanation.  Does it just return a
true/false value?  If so, how does it differ from feof() and/or
ferror()?  What would it do on an interactive stream?  What is the
use case?

[...]

If fpeek had been added to the C90 standard, would you have
considered that to be odd/wrong? If so, why? If not, what form
should it have taken?

I have no opinion on that.

I think I've discussed ESC_STR with you before.

>
But not to the point where these questions were answered:
>
If ESC_STR had been added to the C89 standard, because
a majority of the committee had decided they wanted to
support basic ANSI X3.64, would you have considered that
to be odd/wrong? If so, why? If not, do you think the define
ESC_STR and ESC_CHAR are a bad naming convention,
and if so, what do you think would have been better, and why?
And what header file would you have put them in?
>
If instead, C90 had already been published, and suddenly
committeee members realized they had forgotten about
ANSI X3.64 terminals and quickly formed a C91 standard
to add just this one feature, what header file would you
have put it in, and why?

C90 *could* have added a way to refer to the escape character
(which exists, with different values, in both ASCII and EBCDIC).
The sensible way to do that would have been to allow a \e escape in
character constants and string literals.  Some languages have exactly
that feature, and several C compilers support it as an extension.
No other special character values are defined as named constants
in headers.

Perhaps I would have favored standardizing \e at the time, but that
ship sailed decades ago.  I'd probably favor a proposal to add \e
to C2y.

In practice, if I need an escape character, I use '\x1b'.  I've never
needed to use an EBCDIC escape character.  If I did, I'd use '\x27'.
If I needed to support both ASCII and EBCDIC escape characters,
I'd find a way to do that.  None of this requires language or standard
library support.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */