[gentoo-python] [PATCH 3/3] Initial concept of python-build-r1 eclass.

[Michał Górny]

This eclass handles the build-time-only dependencies on Python. It adds
a one-of dep and finds the best interpreter installed.
---
 gx86/eclass/python-build-r1.eclass  | 172 ++++++++++++++++++++++++++++++++++++
 gx86/eclass/python-r1.eclass        |   2 +
 gx86/eclass/python-single-r1.eclass |   2 +
 3 files changed, 176 insertions(+)
 create mode 100644 gx86/eclass/python-build-r1.eclass

diff --git a/gx86/eclass/python-build-r1.eclass b/gx86/eclass/python-build-r1.eclass
new file mode 100644
index 0000000..d5d1ce0
--- /dev/null
+++ b/gx86/eclass/python-build-r1.eclass
@@ -0,0 +1,172 @@
+# Copyright 1999-2012 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Header: /var/cvsroot/gentoo-x86/eclass/python-single-r1.eclass,v 1.4 2012/11/26 10:05:11 mgorny Exp $
+
+# @ECLASS: python-build-r1
+# @MAINTAINER:
+# Michał Górny <mgorny@g.o>
+# Python herd <python@g.o>
+# @AUTHOR:
+# Author: Michał Górny <mgorny@g.o>
+# Based on work of: Krzysztof Pawlik <nelchael@g.o>
+# @BLURB: An eclass for packages having build-time dependency on Python.
+# @DESCRIPTION:
+# A minimal eclass for packages which need to use the Python interpreter
+# at build-time but have no other relevance to Python.
+#
+# This eclass provides a minimal PYTHON_DEPS variable with a dependency
+# string on any of the supported Python implementations. It also exports
+# pkg_setup() which finds the best supported implementation and sets it
+# as the active one.
+#
+# Please note that python-build-r1 will always inherit python-utils-r1
+# as well. Thus, all the functions defined there can be used in the
+# packages using python-build-r1, and there is no need ever to inherit
+# both.
+#
+# For more information, please see the python-r1 Developer's Guide:
+# http://www.gentoo.org/proj/en/Python/python-r1/dev-guide.xml
+
+case "${EAPI:-0}" in
+	0|1|2|3|4|5)
+		# EAPI=4 needed by python-r1
+		;;
+	*)
+		die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
+		;;
+esac
+
+if [[ ! ${_PYTHON_BUILD_R1} ]]; then
+
+if [[ ${_PYTHON_R1} ]]; then
+	die 'python-build-r1.eclass can not be used with python-r1.eclass.'
+elif [[ ${_PYTHON_SINGLE_R1} ]]; then
+	die 'python-build-r1.eclass can not be used with python-single-r1.eclass.'
+fi
+
+inherit python-utils-r1
+
+fi
+
+EXPORT_FUNCTIONS pkg_setup
+
+if [[ ! ${_PYTHON_BUILD_R1} ]]; then
+
+# @ECLASS-VARIABLE: PYTHON_COMPAT
+# @REQUIRED
+# @DESCRIPTION:
+# This variable contains a list of Python implementations the package
+# supports. It must be set before the `inherit' call. It has to be
+# an array.
+#
+# Example:
+# @CODE
+# PYTHON_COMPAT=( python{2_5,2_6,2_7} )
+# @CODE
+if ! declare -p PYTHON_COMPAT &>/dev/null; then
+	die 'PYTHON_COMPAT not declared.'
+fi
+
+# @ECLASS-VARIABLE: PYTHON_REQ_USE
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# The list of USEflags required to be enabled on the Python
+# implementations, formed as a USE-dependency string. It should be valid
+# for all implementations in PYTHON_COMPAT, so it may be necessary to
+# use USE defaults.
+#
+# Example:
+# @CODE
+# PYTHON_REQ_USE="gdbm,ncurses(-)?"
+# @CODE
+#
+# It will cause the Python dependencies to look like:
+# @CODE
+# || ( dev-lang/python:X.Y[gdbm,ncurses(-)?] ... )
+# @CODE
+
+# @ECLASS-VARIABLE: PYTHON_DEPS
+# @DESCRIPTION:
+# This is an eclass-generated Python dependency string for all
+# implementations listed in PYTHON_COMPAT.
+#
+# Any of the supported interpreters will satisfy the dependency.
+#
+# Example use:
+# @CODE
+# DEPEND="${RDEPEND}
+#	${PYTHON_DEPS}"
+# @CODE
+#
+# Example value:
+# @CODE
+# || ( dev-lang/python:2.7[gdbm]
+# 	dev-lang/python:2.6[gdbm] )
+# @CODE
+
+_python_build_set_globals() {
+	local usestr
+	[[ ${PYTHON_REQ_USE} ]] && usestr="[${PYTHON_REQ_USE}]"
+
+	PYTHON_DEPS=
+	local i
+	for i in "${_PYTHON_ALL_IMPLS[@]}"; do
+		if has "${i}" "${PYTHON_COMPAT[@]}"
+		then
+			local d
+			case ${i} in
+				python*)
+					d='dev-lang/python';;
+				jython*)
+					d='dev-java/jython';;
+				pypy*)
+					d='dev-python/pypy';;
+				*)
+					die "Invalid implementation: ${i}"
+			esac
+
+			local v=${i##*[a-z]}
+			PYTHON_DEPS="${d}:${v/_/.}${usestr} ${PYTHON_DEPS}"
+		fi
+	done
+	PYTHON_DEPS="|| ( ${PYTHON_DEPS})"
+}
+_python_build_set_globals
+
+# @FUNCTION: python-single-r1_pkg_setup
+# @DESCRIPTION:
+# Determine what the best installed (and supported) Python
+# implementation is and set EPYTHON and PYTHON accordingly.
+python-build-r1_pkg_setup() {
+	debug-print-function ${FUNCNAME} "${@}"
+
+	local i rev_impls=()
+	for i in "${_PYTHON_ALL_IMPLS[@]}"; do
+		if has "${i}" "${PYTHON_COMPAT[@]}"; then
+			rev_impls=( "${i}" "${rev_impls[@]}" )
+		fi
+	done
+
+	for i in "${rev_impls[@]}"; do
+		local d
+		case "${i}" in
+			python*)
+				d='dev-lang/python';;
+			jython*)
+				d='dev-java/jython';;
+			pypy*)
+				d='dev-python/pypy';;
+			*)
+				die "Invalid implementation: ${i}"
+		esac
+		local v=${i##*[a-z]}
+
+		if has_version "${d}:${v/_/.}${usestr}"; then
+			python_export "${i}" EPYTHON PYTHON
+			break
+		fi
+	done
+}
+
+_PYTHON_BUILD_R1=1
+fi
diff --git a/gx86/eclass/python-r1.eclass b/gx86/eclass/python-r1.eclass
index c8cfef3..0f62473 100644
--- a/gx86/eclass/python-r1.eclass
+++ b/gx86/eclass/python-r1.eclass
@@ -44,6 +44,8 @@ if [[ ! ${_PYTHON_R1} ]]; then
 
 if [[ ${_PYTHON_SINGLE_R1} ]]; then
 	die 'python-r1.eclass can not be used with python-single-r1.eclass.'
+elif [[ ${_PYTHON_BUILD_R1} ]]; then
+	die 'python-r1.eclass can not be used with python-build-r1.eclass.'
 fi
 
 inherit python-utils-r1
diff --git a/gx86/eclass/python-single-r1.eclass b/gx86/eclass/python-single-r1.eclass
index f645513..60c9977 100644
--- a/gx86/eclass/python-single-r1.eclass
+++ b/gx86/eclass/python-single-r1.eclass
@@ -47,6 +47,8 @@ if [[ ! ${_PYTHON_SINGLE_R1} ]]; then
 
 if [[ ${_PYTHON_R1} ]]; then
 	die 'python-single-r1.eclass can not be used with python-r1.eclass.'
+elif [[ ${_PYTHON_BUILD_R1} ]]; then
+	die 'python-single-r1.eclass can not be used with python-build-r1.eclass.'
 fi
 
 inherit python-utils-r1
-- 
1.8.0