[pacman-dev] Alternatives system brainstorm

[Allan McRae]

On 19/10/19 10:38 pm, Allan McRae wrote:
> On 19/10/19 10:24 pm, Andrew Gregory wrote:
>> On 10/19/19 at 10:15pm, Allan McRae wrote:
>>> On 19/10/19 9:57 pm, Daan van Rossum wrote:
>>>> * on Saturday, 2019-10-19 18:15 +1000, Allan McRae <allan at archlinux.org> wrote:
>>>>
>>>>> /bin/sh -> bash/dash
>>>>> /usr/bin/awk -> gawk/nawk
>>>>> /usr/bin/cc -> gcc/clang
>>>>
>>>> Can we provide alternatives by means of sets of mutually exclusive link packages, using package properties that are already supported in pacman?
>>>>
>>>> sh-bash
>>>> 	provides=('sh')
>>>> 	depends=('bash')
>>>> 	conflicts=('sh-dash')
>>>> sh-dash
>>>> 	provides=('sh')
>>>> 	depends=('dash')
>>>> 	conflicts=('sh-bash')
>>>> bash
>>>> 	depends('sh')
>>>> dash
>>>> 	depends('sh')
>>>>
>>>
>>> Sure - or we could have a system to handle it in a less obtuse manner...
>>>
>>> What happens when a new package wants to provide "sh"?   We need to
>>> rebuild sh-bash and sh-dash?  Easy enough, except that assumes that all
>>> three packages are packaged by the same group.  If bash and dash are
>>> packaged by a distro and the new package by a third party, then the
>>> conflicts provided by the distro are not enough.  But an alternatives
>>> system would work.
>>
>> No rebuilding necessary if the conflicts are changed to just 'sh'.
>> .
>>
> 
> What will happen with "pacman -S dash"?  My initial thought is dash will
> pull in the first provider of sh - sh-bash - which will then pull in bash.

I forgot - pacman queries the user when multiple providers.