Portage uses a cache for most top-level variables (DEPEND
, DESCRIPTION
,
SRC_URI
and so on). This cache may be generated on a different machine, so
these variables must be either static or generated using only unchanging
'version / name' variables (P
, PN
, PV
, PR
, PVR
and PF
).
So, the following will not work:
# DO NOT DO THIS!
if ! has_version "x11-libs/gtk+" ; then
DEPEND="${DEPEND}
gtk? ( >=x11-libs/gtk+-2 )
!gtk? ( =x11-libs/gtk+-1.2* )"
fi
However, this is legal, since versionator.eclass
works upon PV
, and
PV
and PN
are both static:
inherit versionator
if [[ $(get_major_version) -ge 7 ]] ; then
IUSE="${IUSE} tcltk mzscheme"
DEPEND="${DEPEND}
tcltk? ( dev-lang/tcl )
mzscheme? ( dev-lisp/mzscheme )"
RDEPEND="${RDEPEND}
tcltk? ( dev-lang/tcl )
mzscheme? ( dev-lisp/mzscheme )"
if [[ "${MY_PN}" != "vim-core" ]] ; then
RDEPEND="${RDEPEND} !<app-vim/align-30-r1"
fi
fi
Because eclasses modify various cached variables, conditional inheritance is not
allowed except where the same results will always be obtained on every system.
For example, inherits based upon USE
flags are illegal, but inherits based
solely upon PN
are allowed.
As an example of a legal and possibly useful conditional inherit, some eclasses do:
if [[ "${PN##*-}" == "cvs" ]] ; then
inherit cvs
fi
This allows the same eclass to be used for both regular and -cvs
packages.