Re: [gentoo-dev] dependences

[George Shapovalov]

I am not totally up yet, so I apologize in advance if I am getting too 
harsh :).

> depends on SYSTEM PROFILE. In my home page have "graphs" and text files,
> take a look and tell me if gentoo give a tool to get the informations
> that i want: Especifics depends.
>   Thanks!!
> My home: http://www.via-rs.com.br/pessoais/leal
Few comments:
"Linux is a clone of the operating system Unix"
If this goes any serious place, I'd suggest reading up a bit more of 
Unix/Linux history. As it stands now there is no paticular OS called Unix, 
there was a lot of fuss and a lawsuit involving the use of "Unix" and 
everybody for the most part was trying to avoid that name. Plus "clone" is 
soundng too strong, (such wording) may even suggest similarity to the point 
of binary compatibility (contrary to how dissimilar many of "proprietary 
unices" are). But enough on wording.


Now the plots. Lets looks for example at this one (and its series):
http://www.via-rs.com.br/pessoais/leal/Linux/debian-graph284-1.png

Argh, is this a biz prezentation? This is definitely *not* a scientific 
plotting. You said this is a graph (I cannot see on this picture whether 
there are cycles, so I have to believe you), then why don't you use one of 
the standard representations, - top-to-bottom or left-to-right (choice mostly 
depends on figure dimensions and width/depth ratio). Oh, and make it *black 
and white* only and *flat*. Well, color may be used on informal plots but if 
this is aimed to go into the paper it should be BW only. Still the most 
important part is to lay it out differently. As it is now, I cannot gain any 
usefull information and rotating this damn blob will help very little. Your 
data is essentially 2D and mostly tied to one factor, do not try to be 
fancier than it is necessary.

I am sorry man for sounding like an a%*, just doing too many papers 
recently :). My professor would have killed me if I were to try to pull 
something like this by him ;).


> asking you help, to make my work as right as possible. One of
> my principal tasks is determine how much dependences a package
> have. With "qpkg" i have got that informations for my installed
> gentoo system, but the "SYSTEM PROFILE" confuses me. Some packages
> have as dependence the word "SYSTEM PROFILE" that is not a package,
> but too many of them... So i have created a "fake" package "SYSTEM-PROFILE
> " to my tasks... The question is: There is a manner to extract the
> informations that i want, whithout this SYSTEM PROFILE?

Now a short transitional part. What of circular dependencies? At least for 
some "basic" packages they are there (e.g. you need gcc to compile glibc and 
you need glibc for pretty much anything else, but this is way 
oversimplified). Debian hides this from you in their way, Gentoo does not 
exactly hide it, but lets you work around this complication in its own way. 
This is how the SYSTEM PROFILE gets around. 
It is not a package itself but rather a special way to describe what packages 
are considered "special". This includes the ones causing circular deps plus 
the rest of packages that are considered "common" (in a sense of being 
expected to be installed on any Unix-like system). In Gentoo you can select 
any of the multiple profiles provided to you  so that you can match it to the 
task at hand (look into /usr/portage/profiles). So this is what dpkg refers 
to when it says "SYSTEM PROFILE".

Procedural note. At this time I would probably discourage the usage of dpkg as 
it slowly gets obsoleted by portage itself. Instead try 
emerge --pretend --emptytree pkgname
(you can stick world or system instead pkgname there). However !!pay attention 
to what use flags you have selected!! This will vary your dep tree greatly!
I'd suggest to do some serious reading here:
http://www.gentoo.org/doc/en/index.xml#doc_chap3
This should give you a good idea of how package handling is organized in 
Gentoo and what all these use flags are doing. 

Also, if you need deps to be printed as a tree instead of the list, you might 
want to look at portage code. It should not be too difficult to place some 
hooks to make it print self-digested dependency data (before it leys it out 
as a list).

Hope this helps somewhat.

George


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