[MacPorts] #63069: vtk: migrate from python variants to subports

[MacPorts]

#63069: vtk: migrate from python variants to subports
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  Reporter:  mascguy      |      Owner:  stromnov
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:  2.7.2
Resolution:               |   Keywords:
      Port:  vtk          |
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Comment (by mascguy):

 Replying to [comment:14 mascguy]:
 > Replying to [comment:12 Dave-Allured]:
 > > Would someone kindly give me a couple of tips on how to start for
 subports?  I will give this a try.  BTW, update 9.4.0 for VTK is imminent.
 >
 > We have a few ports where we migrated from variants to subports, such as
 `opencv3` and `opencv4`. You can use those as rough examples, to get an
 overall idea.

 I've also started some of the work for `vtk`, in the following branch:
 https://github.com/macports/macports-ports/compare/master...mascguy
 :macports-ports:mascguy-vtk-subports

 One of the key things is to migrate the Python setup to a procedure, so
 that it can be called as needed within each subport. That's mostly done in
 my branch, though it hasn't been tested thoroughly.

 Then it's a matter of defining each subport, and calling the Python setup
 from there.

 Another thing that's needed, is to ensure the subports don't include the
 parent port's contents. That can be done with this snippet, which is used
 in various ports:

 {{{
         # Deconflict with parent port contents
         post-destroot {
             ui_debug "${subport}: python subport: removing parent port
 contents"
             foreach f [exec port -q contents ${name}] {
                 delete ${destroot}${f}
             }
         }
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/63069#comment:15>
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