checking for swig variants in a pre-fetch hook

[Adam Mercer]

Hi

The recent changes to the swig port have broken the scipy build on
Tiger, essentially the problem is that scipy requires the python
variant of swig to be installed. Therefore to try and fix this I want
to check for existence of the python variant using something like the
following pre-fetch hook:

pre-fetch {
  if {![file exists ${prefix}/share/swig/1.3.36/python/python.swg]} {
    ui_error "The python variant of swig is not installed. Please run"
    ui_error "the following commands:"
    ui_error "$ sudo port uninstall swig"
    ui_error "$ sudo port install swig +python"
    error "python variant of swig required"
  }
}

The problem is that this is dependent on the swig version and will
need to be updated for every new swig release. I tried using a
wildcard for the version but this doesn't work. Is there any way that
I can check for this version dependent path in a version independent
way?

Cheers

Adam