On 2019-06-27, Laslo Hunhold <[email protected]> wrote:
> On Thu, 27 Jun 2019 09:10:28 +0200
> Quentin Rameau <[email protected]> wrote:
>
> Dear Quentin,
>
>> I agree, yes is neither a benchmark tool nor a data generator, it just
>> outputs 'y' for piping into other commands.
>> Keep it simple.
>
> I agree with you in general, but are we really "optimizing" yes(1) here
> for the sake of performance? This looks to me like a case of premature
> optimization.
I think we are all on the same page here about simplifying yes(1)
rather than optimizing it. See aidanwillie0317's most recent patch.
> We don't know if a script relies on the behaviour of yes(1) printing
> all passed strings repeatedly. So, even though the tool is not
> standardized by Posix the common "consensus" is that
>
> - with no arguments, it shall print y and a newline repeatedly.
> - with arguments, it shall print them, comma separated, followed by
> newline, repeatedly.
(I think you mean "space separated" here)
How did you determine this consensus? All the BSD implementations I
looked at (OpenBSD, FreeBSD, NetBSD) only support a single argument.
Do you have any examples of scripts relying on this behavior of yes(1)?
> The point about readability is a good one. I will even take the blame
> for writing it as it is now. However, you could greatly improve
> readability without sacrificing features/performance. The line
>
> argv0 = *argv, argv0 ? (argc--, argv++) : (void *)0;
>
> is used in many places in sbase and is more or less an idiom. The
> entire tool itself could then be written as follows. We can even
> remove the checks consequently within the loop, which could be regarded
> as a "performance" improvement.
>
> int i;
>
> argv0 = *argv, argv0 ? (argc--, argv++) : (void *)0;
>
> if (argc == 0) {
> for (;;) {
> fputs("y\n", stdout);
> }
> } else {
> for (;;) {
> for (i = 0; i < argc; i++) {
> fputs(argv[i], stdout);
> fputc(' ', stdout);
This will end up printing an extra space before the newline.
> }
> fputc('\n', stdout);
> }
> }
>
> What do you think? Patch is attached.
This looks pretty good to me. If we decide to support any number of
operands, this seems like the way to do it.
