macports policy of dependencies and installations

[Rodrigo Ventura]

Hi all,

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?

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).

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).

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

Thank you,

Rodrigo Ventura
Institute for Systems and Robotics
(www.isr.ist.utl.pt)
Instituto Superior Técnico
Lisbon, Portugal