Re: RFE: hash-type in sum utils

[Pádraig Brady]

On 08/23/2012 08:55 AM, Ondrej Oprala wrote:
> On 08/22/2012 06:38 PM, Jim Meyering wrote:
>> Eric Blake wrote:
>>> On 08/22/2012 10:05 AM, Pádraig Brady wrote:
>>>> On 08/22/2012 03:00 PM, Ondrej Oprala wrote:
>>>>> Hi, I haven't heard from this thread since I posted the last patch,
>>>>> are there still things to correct or should I consider it closed?
>>>> The --tag description in the texinfo is a bit sparse.  It says:
>>>>
>>>> "If the file is not binary, put a leading whitespace before the
>>>> algorithm's name."
>>>>
>>>> More accurately it could say:
>>>>
>>>> "When operating in @option{--text} mode, put a leading space before
>>>> the algorithm's name.
>>>> On @option{--text} mode significant systems, this enables
>>>> compatibility with existing
>>>> BSD (binary) checksums, while also allowing operating in @option{--text} 
>>>> mode".
>>>>
>>>> It's worth considering though, do we want to support --text mode
>>>> at all with --tag?  I.E. we could avoid the default leading space,
>>>> and have --tag imply --binary and be mutually exclusive with --text?
>>> I'm fine with --tag implying --binary.  --text mode is almost always the
>>> wrong thing to use, and it should have never been the default on
>>> text-mode systems, nor should it be the default output (we're stuck with
>>> that for normal output, where the presence of '*' to indicate binary
>>> output, but only from systems where text mode differs, causes no end of
>>> grief; but for BSD output we don't have to repeat the mistake).
>>>
>>>> I'm 60:40 for having --tag imply --binary given the above.
>>> I'm 90:10 for having --tag imply --binary.
>> I agree wholeheartedly.  Simpler is better.
>>
> Ok, I'm almost done with the changes, I just have one question.
> What should the sum utils do if they get --tag --text as arguments?
> Would it be possible to add BOOL TEXT and end with an error
> if(text && prefix_tag) ?

Yes, if both are specified it should do something like:

if (prefix_tag && text)
  {
    /* This could be supported in a backwards compatible way
       by prefixing the output line with a space in text mode.
       However that's invasive enough that it was agreed to
       not support this mode with --tag, as --text use cases
       are adequately supported by the default output format.  */
    error(0, 0, _("--tag does not support --text mode"));
    usage (EXIT_FAILURE);
  }

thanks!
Pádraig.