From: Dan Cross <cross@math.psu.edu>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] weird print(2) problems...
Date: Wed, 5 Sep 2001 14:23:14 -0400 [thread overview]
Message-ID: <200109051823.OAA03645@augusta.math.psu.edu> (raw)
In-Reply-To: <20010905150808.1FC2619A32@mail.cse.psu.edu>
In article <20010905150808.1FC2619A32@mail.cse.psu.edu> you write:
>>>that if write(2) sees a zero length argument, it should consider that a
>>>nop and return. But then it seems that that would break some weird
>>>semantic somewhere (``Any write will update a timestamp; except for
>>>zero length writes, which are ignored.'' ``Dude, that's broken.'')
>
>it isn't only the possible effect on time stamps; i think it
>should do a write 0 because it's what you said to do.
Yes, that's what I mean by ``breaking some weird semantic'' (although
the semantic isn't that weird). The timestamp thing was just a contrived
example.
>to be fair, it's disguised by print, but even so,
>if i wanted nop() i'd use
> ;
>or
> void nop(void){}
>but i wouldn't call write() or even print. i'd call write() when i wanted
>to write, and i prefer systems that do what i tell it, so that if i say
>`write 0 bytes' i expect it to do that, rather than adding yet
>more special cases to remember.
I don't disagree, but the behavior I've observed is demonstrably broken.
I'm looking for a fix to the system so that the guy writing a program
doesn't have to worry if he's accidentally printing out a blank string;
that's the special case I want to avoid.
After all, if I write zero bytes, I don't expect the program on the
other end of my pipe to stop reading all of a sudden.
> the effect of writing 0 bytes
>is determined by the device, but that's true of writing 1 byte or many,
>so there's no difference there.
Yes there is. When the program I'm piping to reads zero bytes, it stops
reading. If it reads n > 0 bytes, it does not.
>on the other hand, i'd probably write
> if(*str)
> print("%s", str);
>if that's what i wanted.
Sure, that's how I fixed the program at hand (which generates morse
code, btw).
But isn't this also a special case I now need to remember? Worse I
have to remember it when writing user level programs; the complexity
of it (granted, not much) isn't hidden from me. It's a bummer;
surely there's an elegant solution to this problem.
- Dan C.
next prev parent reply other threads:[~2001-09-05 18:23 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-09-05 15:11 forsyth
2001-09-05 18:23 ` Dan Cross [this message]
2001-09-05 19:10 ` Boyd Roberts
-- strict thread matches above, loose matches on Subject: below --
2001-09-11 11:16 rob pike
[not found] <rsc@plan9.bell-labs.com>
2001-09-05 21:11 ` Russ Cox
2001-09-05 21:24 ` Scott Schwartz
2001-09-05 19:46 Russ Cox
2001-09-05 19:19 Russ Cox
2001-09-05 19:40 ` Boyd Roberts
2001-09-06 8:19 ` Matthew Hannigan
2001-09-06 16:18 ` Douglas A. Gwyn
2001-09-06 20:45 ` Boyd Roberts
2001-09-05 18:40 Russ Cox
2001-09-05 19:58 ` Dan Cross
[not found] <cross@math.psu.edu>
2001-09-04 19:02 ` Dan Cross
2001-09-04 19:08 ` Scott Schwartz
2001-09-05 14:22 ` Dan Cross
2001-09-05 19:01 ` Boyd Roberts
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