[MacPorts] #54216: zlib +ng (and +cloudflare) accelerated variants

[MacPorts]

#54216: zlib +ng (and +cloudflare) accelerated variants
--------------------------+------------------------
  Reporter:  RJVB         |      Owner:  ryandesign
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:  haspatch
      Port:  zlib         |
--------------------------+------------------------

Comment (by RJVB):

 Of course path:-style depspecs work, and of course you can change them
 with a single search/replace, that's not the issue.

 But they're not very nice to enter or maintain, and it takes only a single
 portfile change (or new port) to forget using it to break things for
 people who have an alternative port installed. (You also introduce a
 platform-dependency through the dylib extension, but that only concerns
 hoopleheads like me who maintain most of their ports to function on Linux
 too.)

 Maybe we could consider writing a PortGroup that provides depspecs for all
 commonly used archivers; zlib is likely not the only one for which
 alternative implementations exist. A batch change to make all ports use
 that PG will be a lot trickier though, and

 {{{
 > port echo depends:zlib | wc -l
 836
 }}}

 > otherwise it would be the unwieldy `sudo port -n upgrade --enforce-
 variants -ng +cloudflare`

 I think you're still confusing things. `Port install` always allowed you
 to install another build variant, but it won't deactivate a conflicting
 port - how would it know which to deactivate (as long as "base" doesn't
 provide a `provides foo` or `alternative_for foo` syntax)?
 The unwieldy form is for upgrading a port and changing variants at the
 same time (I think, I've seen the hints to use it but never have).

 What you need to change between alternatives is something like

 {{{
 > port-swap-active alternative1 alternative2
 }}}
 (https://github.com/RJVB/macstrop/blob/master/macports/bin/port-swap-
 active)

 OT: I should extend that script to allow swapping "families" of ports in a
 single call.

--
Ticket URL: <https://trac.macports.org/ticket/54216#comment:8>
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