macports policy of dependencies and installations

[Ryan Schmidt]

On Oct 24, 2008, at 06:25, Rodrigo Ventura wrote:

> I've just switched from Panther to Leopard, and decided to remove  
> my previous macports installation and restart afresh. I'v been  
> installing some software, namely playerstage suite, but I'm  
> wondering why macport needs to install so much already available  
> software in the Leopard system. For instance, what sense does it  
> make to re-install libz 1.2.3 if Leopard come with that same  
> version, and perl? and m4? and xorg?

If a new version of e.g. zlib is released, we want users to update to  
it, and do not want to be at the mercy of Apple's update schedule.  
Different versions of Mac OS X have different versions of libraries.  
Leopard is very different from Tiger and earlier. By making MacPorts  
use only its own stuff, we make MacPorts as consistent as possible  
between different users on different operating systems.

> I feel like building an operating system from scratch, in /opt/ 
> local, with all potential conflicts with the Leopard base system  
> (since /opt/local/bin has to be in PATH in order for macports to be  
> useful).

None of it will conflict with what Leopard provides. That's the point  
of isolating it in a separate prefix (/opt/local).

> Moreover, I suspect that some difficulties compiling software  
> (e.g., PIL), as for instance compilation complains libz does not  
> support PPC (of course! macport's libz, same version as Leopard's,  
> but without PPC support, is superimposing in PIL's built script lib  
> search path).

Sounds like PIL needs a universal version of zlib. The solution is to  
install the zlib port with the universal variant.

sudo port -f uninstall zlib
sudo port clean zlib
sudo port install zlib +universal

> Can anyone shed some light on this? Or point me towards some FAQ  
> question clearing this up?

http://trac.macports.org/wiki/FAQ#WhyisMacPortsusingitsownlibraries