Re: [gentoo-portage-dev] handling config stuff in portage (for package compression, etc)

[Jason Pepas]

On Mon, Nov 07, 2005 at 12:11:55AM +0100, Marius Mauch wrote:
> > For example, if Z="bzip2", a file would be sourced ("bzip2.sh"), which
> > would contain the these settings:
> >
> > ZEXT="bz2"
> > TZEXT="tbz2"
> > ZCOMPRESS="bzip2"
> > ZDECOMPRESS="bunzip2"
> > ZFILTER="bzip2"
> > ZUNFILTER="bunzip2"
> > ZRECOMPRESS="no"
>
> Why this indirection? Just for convienience or are there technical
> reasons? If it's just convienience then you don't need this, just
> utilize the "source" command in make.conf. Anyway, there is no place for
> one-letter vars in make.*

I see no way of avoiding making things hard coded without making a
sepparate file for each compression method.

> > The following subsystems would "source" one of these files to get
> > their settings:
> >
> > PKG_
> > DOC_
> > MAN_
> > INFO_
> >
> > possibly others.
> >
> > So, if PKG_Z="bzip2", bzip2.sh would be read to set PKG_ZEXT,
> > PKG_TZEXT, PKG_ZCOMPRESS, etc.
>
> Why are those vars needed? Can't they be directly derived from the
> global ones?

Without these vars, how would you use bzip2 for packages but use gzip
for man pages (as the current gentoo does)?  The global ones would all
be specific to one method of compression...

> > As these module files are sourced, individual config options could be
> > overridden via values in the environment.  For example, if I wanted
> > gzip used across the board, but I wanted different levels of
> > compression for man pages and packages, I could do this in make.conf:
> >
> > Z="gzip"
> > PKG_ZCOMPRESS="gzip --best"
> > MAN_ZCOMPRESS="gzip --fast"
>
> Somehow this part looks like overengineering to me. Doesn't seem worth
> to introduce 7*4=28 new vars just for this.

Yeah, this is the problem I am stuck at: adding 28 new vars is
ridiculous, but I am having trouble seeing another way of doing this, so
I asked the mailing list.

I thought about it some more and perhaps a better way of doing this
would be to only specify the method of compression for each subsystem
using env vars.  So, you would only have:

PORTAGE_COMPRESS_PKG
PORTAGE_COMPRESS_MAN
PORTAGE_COMPRESS_DOC
PORTAGE_COMPRESS_INFO

Then, something internal to portage would take the value of that var and
lookup the rest of what was needed somewhere else.

-jason pepas
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