[MacPorts] #25330: sane-backends 1.0.21 and variants to limit which backends are built

[MacPorts]

#25330: sane-backends 1.0.21 and variants to limit which backends are built
----------------------------------------------+-----------------------------
 Reporter:  aguynamedryan+macports@…          |       Owner:  macports-tickets@…                   
     Type:  enhancement                       |      Status:  new                                  
 Priority:  Normal                            |   Milestone:                                       
Component:  ports                             |     Version:  1.9.1                                
 Keywords:                                    |        Port:  sane-backends                        
----------------------------------------------+-----------------------------
 I have made the following updates to the sane-backends Portfile
  * updated to build sane-backends 1.0.21
    * set revision to 0
    * updated checksums
  * listed myself as the maintainer
  * set use_parallel_build to yes

 I've made the following enhancement:

 I noticed that the command:
 {{{
 scanimage -L
 }}} runs very slowly and the debug messages from SANE_DEBUG_DLL seem to
 indicate that scanimage takes a long time to run through each of the 75
 backends when it searches for scanners.

 It is possible to build sane-backends with a subset of the backends by
 setting the environment variable BACKENDS to the list of backends you'd
 like to compile before you run ./configure.

 Accordingly, I made variants for the 75 backends in the sane-backends
 Portfile so a user can now run install like so:
 {{{
 port install sane-backends +net +hp +fujitsu
 }}}
 to build only the net, hp, and fujitsu backends.  This made scanadf run
 faster for me since it had fewer backends to iterate through.  As a bonus,
 compilation also takes far less time if just a few backends are specified.

 I'm new to TCL and I'm not sure the way I specified the variants is
 particularly efficient, but it works.  If there is a better way to
 structure the variants in the Portfile I'd love to learn.

-- 
Ticket URL: <http://trac.macports.org/ticket/25330>
MacPorts <http://www.macports.org/>
Ports system for Mac OS