[pacman-dev] Alternatives system brainstorm

[Allan McRae]

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.

A