Re: [gentoo-dev] Re: RFC: fortran-2.eclass to depend on virtual/fortran

[justin]

On 10/7/12 7:36 PM, Jonathan Callen wrote:
> On 10/07/2012 01:20 PM, justin wrote:
>> Hi,
>
>> I want to add following change to fortran-2.eclass to achieve more
>> simpler usage.
>
>> The patch will make the eclass depend on virtual/fortran so that
>> no manual addition is needed. Two exception are present, a) the
>> ebuild has the USE flag fortran, then we check for that, or b) the
>> FORTRAN_OPTIONAL variable is set, which leaves the control to the
>> ebuild (e.g. for cases like "lapack? ( virtual/fortran )").
>
>> This is the best coverage of the use cases present, because
>
>> * most ebuild using the eclass want to have a fortran compiler *
>> most other trigger optional fortran support through USE=fortran *
>> only minor have different USE for this purpose (e.g. numpy)
>
>> Thanks for comments,
>
>> Justin
>
>
> You cannot check the value of IUSE in global scope in an eclass, as at
> least portage actually unsets it before sourcing an eclass (also, it
> is not defined in PMS what value IUSE would have at that point).  You
> also got a conditional backwards -- if you don't set FORTRAN_OPTIONAL
> with that patch, then *nothing* gets appended to DEPEND -- if you do
> set it, then DEPEND="virtual/fortran" will always be set (with your
> current logic).
>
>

Regarding your first point I copied the behavior from the
toolchain.eclass and I thought it would work. Testing it, I see you are
right. Any suggestion how to check for a USE being IUSE in an eclass?

NAd your second point is completely right. I fix this when we sorted out
the USE check.

Thanks
Justin