[pacman-dev] Alternatives system brainstorm

[Allan McRae]

On 19/10/19 10:41 pm, Allan McRae wrote:
> 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.
> .
> 

$ pacman -S b
resolving dependencies...
:: There are 2 providers available for foo:
:: Repository test
   1) a-foo  2) b-foo

Enter a number (default=1):

It just picks the wrong one by default...