Default variants

[Rainer Müller]

N_Ox wrote:
> 
> Le 14 août 07 à 19:58, N_Ox a écrit :
> 
>>
>> Le 12 août 07 à 05:28, N_Ox a écrit :
>>
>>> From what I've understood, the problem with default variants is that
>>> if we do something like `port foo -bar` and that foo has
>>> `default_variants +bar`, if an upgrade of foo is released, then `port
>>> upgrade foo` will enable bar variant because variant disabling are
>>> not saved and `default_variants +bar` will be evaluated.
>>>
>>> Is this really a problem?
>>> Can't we use the magic of the TCL interpreter and ignore the call to
>>> default_variants procedure in upgrade variant?
>>>
>>> These were my $0.02 for tonight...
>>> ...I'll now take my pills and go to bed :p
>>>
>>
>> Another problem with default_variants are variant conflicts.
>> Something among those lines:
>>
>> variant apache2 {...}
>> variant apache conflicts apache2 {...}
>> default_variants +apache2
>>
>> and this port command:
>> port install +apache
>>
>> would produce an error because that would select apache and apache2.
>>
>> So here is my idea: let's create a new block named variant_group, or
>> variant_choice, or even both.
>>
>> variant_(group|choice) webserver {
>>     variant apache2 {...}
>>     variant apache {...}
>> }
>>
>> variant_group would tell us that we _can_ enable support for _one_
>> webserver, namely apache or apache2.
>> variant_choice would tell us that we _must_ enable support for _one_
>> webserver, namely apache or apache2.
>>
>> That's all for today.
>> Regards,
>>
> 
> Almost all...
> I've forgotten something:
> 
> default_variants +apache2 and port install +apache would not fail and
> would automagically select apache instead of +apache2.

No one commented on this yet, so I will do start the discussion. I think
this is a very reasonable idea to group variants to make it easier to
implement choices. I also remember that we have some port having a
choice between gnutls and openssl, so this is really a common use case.
But there is still the need to record disabled default variants in order
for this to work.

Rainer