[MacPorts] #50969: Provide a generic extract (and compress) commands in base

[MacPorts]

#50969: Provide a generic extract (and compress) commands in base
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  Reporter:  mojca@…      |      Owner:  raimue@…
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  base         |    Version:  2.3.4
Resolution:               |   Keywords:
      Port:               |
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Comment (by rjvbertin@…):

 No, in my current case there is also the issue that the main file uses a
 different compression scheme, so putting the additional file in distfiles
 will cause the extraction phase to fail.

 However, one can think of other scenarios where one would want to download
 additional file(s) outside of the regular mechanism mostly designed for
 source files. Configuration, templates, data, there are many kinds of
 additional things a port could want to provide automatically when it is
 (re)installed, that are kept up-to-date upstreams but for which the
 installed software doesn't provide an integrated updating mechanism.

 I admit, it's still a bit far-fetched. OTOH, almost all the work has been
 done, cf. my example `file_fetch` procedure above.

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Ticket URL: <https://trac.macports.org/ticket/50969#comment:6>
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