[MacPorts] #16336: Allow multiple ports to satisfy a single dependency

[MacPorts]

#16336: Allow multiple ports to satisfy a single dependency
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  Reporter:  rhwood at macports.org  |       Owner:  macports-tickets at lists.macosforge.org
      Type:  enhancement          |      Status:  new                                  
  Priority:  Normal               |   Milestone:  MacPorts base enhancements           
 Component:  base                 |     Version:  1.6.0                                
Resolution:                       |    Keywords:                                       
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Comment (by macsforever2000 at macports.org):

 Replying to [comment:7 ryandesign at macports.org]:
 > What is the advantage to a "port:a|b|c" syntax? If all these ports
 provide the same thing, then "path:${prefix}/some/file:a" (where
 ${prefix}/some/file is a file provided by all three ports) is sufficient,
 isn't it?

 Sometimes the dependency requires the entire port, not just a single file.
 For example, in the bacula port it requires a database be installed (when
 not using the client-only variant) but it really doesn't matter which
 precise version it is. To work around this, I had to create variants for
 each database version which is cumbersome. So instead of creating a
 variant for postgresql83, postgresql82, postgresql81 AND postgresl80, I
 decided to only use the latest version. However, it would be better to
 just have had a "postgresql8" variant which required any of them. The
 provides keyword would not work in this case.

 However, it brings up an issue. If none of the ports are available, which
 one gets installed? The first one in the list?

 I fully agree that the provides keyword is also a great idea. But it seems
 limited in usefulness to devel type ports only.

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Ticket URL: <http://trac.macports.org/ticket/16336#comment:8>
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