Perl 5.8.8 already present on Leopard; can I make a "dummy" Portfile?

[Ryan Schmidt]

On Jan 17, 2008, at 09:44, Philip K.F. Hölzenspies wrote:

> On Thursday 17 January 2008 16:21:16 Ryan Schmidt wrote:
>
>> http://trac.macosforge.org/projects/macports/wiki/
>> FAQ#WhyisMacPortsusingitsownlibraries
>
> I did indeed read this, but my point is slightly more subtle. Allow  
> me to go
> through the entry in the FAQ in an inline manner:
>
> <quote>
> First, it makes ports more compatible across different versions of  
> Darwin/OS
> X. If we can rely on e. g. openssl 0.9.8 from MacPorts, we don't  
> have to test
> every port that needs ssl for every available openssl installation.
> </quote>
>
> My point was actually about a Portfile of a very specific version  
> of perl
> (5.8.8), which happens to be exactly that version which comes with  
> Leopard.
> This means that you only assume the default installation and only if
> explicitly mentioned in the Portfile. Thus, only the Portfile for  
> perl5.8
> with version 5.8.8 would have a section for platform darwin 9 that  
> exempts
> from actually installing it. This is consistent with the  
> observation that
> MacPorts didn't actually bother installing it's own gcc, but rather  
> simply
> keep on using the gcc installed with the DT package.
>
> <quote>
> Apple's software tends to break from time to  time (e. g. openssl  
> refuses to
> build with an old zlib, but Apple shipped theold headers of the  
> vulnerable
> zlib version).
> </quote>
>
> Absolutely true. However, when Apple shifts broken software, it  
> does so with a
> version of the OS. Tiger contained a funky version of libgmp IIRC,  
> in which
> case the libgmp Portfile for the version installed on Tiger would  
> NOT exempt
> from installing when on a darwin 8 platform.

Sometimes Apple installs modified versions of software. For example,  
Apple includes "gcc 4.0.1" with Xcode, but it's a modified version of  
gcc 4.0.1. I don't know whether Apple's perl 5.8.8 is a modified  
version or not. Therefore, it's simpler to always install the  
MacPorts version when perl is required. Also, the rest of the ports  
that use perl will assume that it and all its parts are somewhere  
under ${prefix}. If we were to use the system's perl sometimes, this  
assumption would sometimes not be true. Again, it's simpler to always  
use MacPorts perl. It would probably be possible to support what you  
propose, but I feel it would take considerable effort to implement  
it, and I see no benefit to doing so. Finally, it makes things less  
predictable. It's much easier to explain that "MacPorts perl always  
gets used" than it is to explain "MacPorts perl gets used except in  
these very specific circumstances."

Note that some ports do require a more up-to-date gcc, or features  
which "normal" gcc provides which Apple gcc doesn't, and therefore do  
depend on, say, the gcc42 port.


> <quote>
> Third reason is up-to-dateness: Apple only features e. g. Python  
> 2.3, not 2.4,
> with which some software does not work. The drawbacks on this  
> behaviour also
> are minimal: Wasting 10MB for a Python installation is next to  
> nothing if you
> have a GB-harddisk and gain consistency all the way in return.
> </quote>
>
> This point still holds. When Portfiles for perl5.8 with version  
> 5.8.9 and
> 5.8.10 do not have an exemption for darwin 9, they're simply  
> installed. The
> quote above is slightly optimistic, however, in assuming a general
> up-to-dateness of MacPorts own portfile tree. This is not true,  
> though. Like
> I said, ghc required Perl 5.8.8, but the tree contains packages for  
> 5.8.9 and
> 5.8.10 as well. When another package requires 5.8.9, is perl  
> installed twice?
> When yet another package wants 5.8.10, is it installed yet another  
> time? If
> this is not the case, what happens with perl 5.10?

We have a portfile perl5.8 which installs perl 5.8.8 and a portfile  
perl5.10 which installs perl 5.10.0. Those are the only two versions  
of perl that can be installed with MacPorts at this time. If and when  
perl 5.8.9 or 5.8.10 is released by the perl developers, the perl5.8  
port will be updated to that version (and then perl 5.8.8 will no  
longer be available for installation with MacPorts). MacPorts does  
not allow you to arbitrarily specify what version of a port to  
install. You can only install the latest version of a given port.  
(You can install an older version if you really really want to, but  
you have to fiddle with it behind MacPorts' back to do so.)  
Similarly, portfiles cannot depend on a specific version of a given  
port. They can only depend on a specific port.