[MacPorts] #18359: Guide has wrong advice about variants

[MacPorts]

#18359: Guide has wrong advice about variants
-------------------------------------+--------------------------------------
 Reporter:  ryandesign@…             |       Owner:  markd@…                
     Type:  defect                   |      Status:  new                    
 Priority:  Normal                   |   Milestone:  Website & Documentation
Component:  guide                    |     Version:  1.7.0                  
 Keywords:                           |        Port:                         
-------------------------------------+--------------------------------------
 The Guide [http://guide.macports.org/#development.variants.phase says
 this] of variants:

  If a variant requires options in addition to those provided by keywords
 using -append and/or -delete, in other words, any actions that would
 normally take place within a port installation phase, do not try to do
 this within the variant declaration. Rather, modify the behavior of any
 affected phases when the variant is invoked using the variant_isset
 keyword.

 {{{
 post-destroot {
     xinstall -m 755 -d ${destroot}${prefix}/etc/
     xinstall ${worksrcpath}/examples/foo.conf \
         ${destroot}${prefix}/etc/

     if {[variant_isset carbon]} {
         delete ${destroot}${prefix}/bin/emacs
         delete ${destroot}${prefix}/bin/emacs-${version}
     }
 }
 }}}

 I do not know why the Guide says this because it is the opposite of what I
 recommend. It should say something more like:

  If a variant requires options in addition to those provided by keywords
 using -append and/or -delete, in other words, any actions that would
 normally take place within a port installation phase, include these within
 the variant declaration if possible, so that it is easier to see at a
 glance what a variant does. If you want to take an action if a variant is
 *not* set, use the variant_isset keyword.

 {{{
 post-destroot {
     xinstall -d ${destroot}${prefix}/share/emacs/${version}/leim
     delete ${destroot}${prefix}/bin/ctags
     delete ${destroot}${prefix}/share/man/man1/ctags.1
 }

 variant carbon conflicts x11 description {Adds a Mac (Carbon) version of
 Emacs} {
     configure.args-delete   --without-carbon
     configure.args-append   --with-carbon \
                             --enable-carbon-app=${applications_dir}
     post-destroot {
         delete ${destroot}${prefix}/bin/emacs
 ${destroot}${prefix}/bin/emacs-${version}
     }
 }

 post-activate {
     if {![variant_isset carbon]} {
         ui_msg "Note: You have not selected the +carbon variant"
     }
 }
 }}}

-- 
Ticket URL: <http://trac.macports.org/ticket/18359>
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