Adding configure options when installing a port

[Scott Webster]

On Thu, Jun 17, 2010 at 11:44 AM, Ryan Schmidt <ryandesign at macports.org> wrote:
> On Jun 16, 2010, at 19:31, Stephen Langer wrote:
>
>> Therefore it's a serious mistake for a packaging system to assume that it's ok to enable openmp in libraries.   A quick solution would be to provide both openmp and no-openmp variants, which would make users choose between fast stand-alone ImageMagick programs and libraries that can be linked by threaded apps.
>
> We don't need two variants; we only need one variant, "openmp", which the user can either enable or disable. It just remains a question as to whether the variant should be enabled by default or not. What I'm hearing is that we should disable it by default.
>

I'm not entirely sure I agree with disabling by default.  Unless I was
reading this list, I would never have known about this issue, and
would just go with the default.  Disabling openmp would slow down
everything (well, not quite everything I guess) I do with ImageMagick
by a factor of 2.  Same would happen with other ports that can use
openmp if it was disabled there...

I guess I'm just saying that there is a trade-off between universal
compatibility and speed here.  I don't have a good handle on how big
of an issue the compatibility thing is.  If it's quite isolated then I
think having the twice (or more) as fast option as default is
reasonable.