From tom@@@k@||ber@ @end|ng |rom gm@||@com  Wed Nov  4 16:26:12 2020
From: tom@@@k@||ber@ @end|ng |rom gm@||@com (Tomas Kalibera)
Date: Wed, 4 Nov 2020 16:26:12 +0100
Subject: [Rd] sprintf, check number of parameters
In-Reply-To: <1MyKDU-1kQFdI0KZI-00yjJP@mail.gmx.com>
References: <1MyKDU-1kQFdI0KZI-00yjJP@mail.gmx.com>
Message-ID: <cd471ca4-2322-95f1-7975-a71594cf8df2@gmail.com>


Dear Matthias,

On 11/4/20 4:01 PM, matthias-gondan wrote:
> Dear Tomas,
>
> Thank you.
>
> Regarding the "unnumbered" arguments, i.e. sprintf('%f %f', 1, 2, 3). 
> This was the case I wanted to report, here a warning can be very useful.
>
> Regarding the "numbered" arguments, that is, sprintf('%$1f %$3f', 1, 
> 2, 3). Here, omission of an argument might be intended, for example, 
> in an application with support for multiple languages. Therefore, I am 
> wondering if a warning should be raised.

It is rather "%$1f", etc.

Say GCC warns also on unused arguments with numbered references ("unused 
arguments in $-style format"). I have not yet received any feedback from 
package maintainers who would have found a problem with the new warning 
for message translation. Would you have an example pattern that should 
be supported? Shouldn't all arguments be used, anyway, just possibly in 
different order?

Unless there is a strong reason to do otherwise, I would rather not 
introduce more deviations from the C behavior. Of course, technically it 
would be simple: not print a warning when there is at least one numbered 
reference.

Best
Tomas

> Regarding the mixture: never heard that this works, and I would 
> probably not want to use it...
>
> Your work is much appreciated, thanks again.
>
> Best regards,
>
> Matthias
>
>
> -------- Urspr?ngliche Nachricht --------
> Von: Tomas Kalibera <tomas.kalibera at gmail.com>
> Datum: 04.11.20 15:43 (GMT+01:00)
> An: Matthias Gondan <matthias-gondan at gmx.de>, r-devel at r-project.org
> Betreff: Re: [Rd] sprintf, check number of parameters
>
> Dear Matthias,
>
> thanks for the suggestion, R-devel now warns on unused arguments by
> format (both numbered and un-numbered). It seems that the new warning is
> useful, often it finds cases when arguments were accidentally passed to
> sprintf but had been meant for a different function.
>
> R allows combining both numbered and un-numbered references in a single
> format, even though it may be better to avoid and POSIX does not allow
> that.
>
> Best
> Tomas
>
> On 9/20/20 1:03 PM, Matthias Gondan wrote:
> > Dear R developers,
> >
> > I am wondering if this should raise an error or a warning.
> >
> >> sprintf('%.f, %.f', 1, 2, 3)
> > [1] "1, 2"
> >
> > I am aware that R has ?numbered? sprintf arguments (sprintf('%1$.f', 
> ?), and in that case, omissing of specific arguments may be intended. 
> But in the usual syntax, omission of an argument is probably a mistake.
> >
> > Thank you for your consideration.
> >
> > Best wishes,
> >
> > Matthias
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
>


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[Rd] sprintf, check number of parameters
Tomas Kalibera