Date: Fri, 15 Aug 2014 15:42:41 -0400 From: "Garance A Drosehn" <drosih@rpi.edu> To: arch@freebsd.org Subject: Re: XML Output: libxo - provide single API to output TXT, XML, JSON and HTML Message-ID: <5B031AE6-100F-4AD7-B721-F0FF207CAE3E@rpi.edu> In-Reply-To: <53ED578B.6070205@freebsd.org> References: <20140814052648.GM2737@kib.kiev.ua> <201408140606.s7E66XXA091972@idle.juniper.net> <20140814085257.GN2737@kib.kiev.ua> <201408140847.00573.jhb@freebsd.org> <94A47A7D-89C9-4504-B669-2A5EDA80373B@bsdimp.com> <53ED578B.6070205@freebsd.org>
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On 14 Aug 2014, at 20:42, Alfred Perlstein wrote:
> On 8/14/14 9:13 AM, Warner Losh wrote:
>> My question for people advocating this method: Why not require all
>> commands
>> that generate this kind of output to support a standard command line
>> option
>> that causes the command to print nothing and return 0 if it supports
>> reporting,
>> or anything else if it doesn’t (return 0 with output, or return
>> non-zero with or without
>> output). This would handle the more complicated implementation issues
>> with using
>> DT_NEEDED and/or the ELF note, be more in line with how things are
>> traditionally
>> done, and offer greater flexibility of implementation.
>>
>> Warner
> This is a decent idea, however the problem is firstly that most
> short-opts are taken, second issue is that adding getopt_long to a
> whole slew of programs will make the effort take a long time. It's
> really better to limit scope of this such that we are just making
> machine readable output.
>
> -Alfred
[-- try #2 with this reply. arg. --]
In the case of adding just one long option, you don't have to add
getopt_long() to any programs. The main program would only need:
/* - - - - - - - - - - - - - - - - - - - */
/* Apologies if my email client totally mangles the following source */
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#define COMMON_LONG_ARG "-—supports-xml"
int
main(int argc, char **argv)
{
/* note this whole check could be a macro pulled from some
* include file */
if (argc == 2) {
argv++;
if (0 == strcmp(*argv, COMMON_LONG_ARG)) {
return (0);
}
}
printf("... Standard processing of %d arguments...\n", argc);
/* I'm returning "1" here to mimic what would happen
* in a command which did *not* have the above check.
*/
return (1);
}
/* - - - - - - - - - - - - - - - - - - - */
I think we could do better than the suggestion Warner gave, but his
suggestion is pretty trivial to implement. It gets a little messier
if we want to support multiple xo-related parameters, but again we
could put all that standard processing in a library subroutine, and
each program which has libxo would call that standard libxo-options
routine before calling anything else in the unix command.
--
Garance Alistair Drosehn = drosih@rpi.edu
Senior Systems Programmer or gad@FreeBSD.org
Rensselaer Polytechnic Institute; Troy, NY; USA
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