Re: [gentoo-dev] Ebuild interactivity

[Drake Wyrm]

On Sat, 2004-05-01, 05:11:55 -0500, in <409377EB.2050707@g.o>,
Joshua Brindle <method@g.o> wrote:
> If this must be done (and it seems like there is pressure to do so) I
> believe the best way is to expand the profile/global/conf language to
> support such choices. For example, if an app needs a mysql host and db
> that can have a 'default' value in the profile (ugh) or the
> make.global file, like MYSQL_HOST, MYSQL_DB. These would be defaults
> just like all other aspects of gentoo (like default CFLAGS, default
> USE vars, etc) and would be overridden by the user in make.conf.
>
> Ebuilds that use such variables could add a warning:
>
> *WARNING: Current MYSQL_HOST is localhost (default) *WARNING: Change
> this in make.conf if you need to
>
> then you get rid of the interactivity problem.. the only problem with
> this is a bloated make.global that has variables for probably every
> database type available, etc but it's still a more elegant way than
> asking for input when the ebuild is used.

A while back, I suggested adding a new function, pkg_depend(), to the
ebuild engine. The context was handling complicated dependencies, but
I've given this some additional thought. Such a function could solve a
number of other problems mentioned in the last month or so.

pkg_depend() would either report the prerequisites for a package to
Portage, or check for them, depending on whether the ebuild was
currently being scanned for metadata, or actually being built. 

This function would call a number of need_* functions. The first were
need_dep() and need_rdep(), to specify package dependencies. Just as an
example of what I'm thinking:

	pkg_depend() {
		need_rdep '>=net-www/apache-2*' || die
		need_dep '|| ( virtual/aspell-dict app-text/ispell
			app-text/hspell )' || die
		need_dep 'sys-devel/gcc' || die
	}

	need_dep() {
		newdepend "$1"
		if [ "${EBUILD_PHASE}" != "depend" ]
		then
			has_version "$1"
			return $?
		fi
		return 0
	}

The `need_dep()` function returns success during the depend phase, but
when `pkg_depend()` is called from dyn_setup, for example, it can raise
an error.

Problems:
	* portageq can't handle dynamic dependencies; `has_version '|| (
	  foo bar) always returns failure
	* this conficts with the noauto feature

Remember the discussion about three weeks ago, regarding better ways to
handle adding system users. The conversation was dropped, because there
is little chance that Portage will ever be able to, for example, add
users to an LDAP server. Still, we need a way to specify that a package
requires a particular user to be available.

	need_user apache || die "User 'apache' not available"

Problems:
	* I don't know of any easy way to ask the system to resolve,
	  from the command line, a username. Grepping the passwd file
	  works when users are authenticated locally, but that's not the
	  situation this is supposed to solve.

Now for optional and required configuration options:

	need_config MYSQL_HOST || die "must define MYSQL_HOST"
	need_config MYSQL_DB || die "must define MYSQL_DB"
	use_config THISPACKAGE_PORT # defaults to tcp:42

Problems:
	* namespace issues
	* when to inform the sysadmin? `emerge -pv`, perhaps?
	* I really need to apply to be a developer, instead of just
	  making random suggestions now and then.


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