[RFC] support for optional dependencies in package.env

Index: java-utils-2.eclass
===================================================================
RCS file: /var/cvsroot/gentoo-x86/eclass/java-utils-2.eclass,v
retrieving revision 1.87
diff -u -B -r1.87 java-utils-2.eclass
--- java-utils-2.eclass	27 May 2007 11:09:11 -0000	1.87
+++ java-utils-2.eclass	27 May 2007 23:43:05 -0000
@@ -1078,7 +1078,6 @@
 # Intended for binary packages where you don't need to symlink the jars or get
 # their classpath during build. As such, the dependencies only need to be
 # specified in ebuild's RDEPEND, and should be omitted in DEPEND.
-# Get the classpath provided by any number of packages.
 #
 # @param $1 - comma-separated list of packages, or a single package
 # @param $2 - if param $1 is a single package, optionally specify the jar
@@ -1123,6 +1122,57 @@
 }
 
 # ------------------------------------------------------------------------------
+# @ebuild-function java-pkg_register-optional-dependency
+#
+# Registers optional runtime dependency on a package, list of packages, or a
+# single jar from a package, into package.env OPTIONAL_DEPEND line. Can only be
+# called in src_install phase.
+# Intended for packages that can use other packages when those are in classpath.
+# Will be put on classpath by launcher if they are installed. Typical case are
+# JDBC implementations for various databases. It's better than having USE flag
+# for each implementation triggering hard dependency.
+#
+# @param $1 - comma-separated list of packages, or a single package
+# @param $2 - if param $1 is a single package, optionally specify the jar
+#   to depend on
+#
+# Example: Record the optional dependency on whole xerces-2 and xalan,
+#	java-pkg_register-optional-dependency xerces-2,xalan
+# Example: Record the dependency on ant.jar from ant-core
+#	java-pkg_register-optional-dependency ant-core ant.jar
+#
+# Note: Passing both list of packages as the first parameter AND specifying the
+# jar as the second is not allowed and will cause the function to die. We assume
+# that there's more chance one passes such combination as a mistake, than that
+# there are more packages providing identically named jar without class
+# collisions.
+# ------------------------------------------------------------------------------
+java-pkg_register-optional-dependency() {
+	debug-print-function ${FUNCNAME} $*
+
+	java-pkg_check-phase install
+
+	[[ ${#} -gt 2 ]] && die "${FUNCNAME} takes at most two arguments"
+
+	local pkgs="${1}"
+	local jar="${2}"
+
+	[[ -z "${pkgs}" ]] && die "${FUNCNAME} called with no package(s) specified"
+
+	if [[ -z "${jar}" ]]; then
+		for pkg in ${pkgs//,/ }; do
+			java-pkg_record-optional-jar_ "${pkg}"
+		done
+	else
+		[[ ${pkgs} == *,* ]] && \
+			die "${FUNCNAME} called with both package list and jar name"
+		java-pkg_record-optional-jar_ "${pkgs}" "${jar}"
+	fi
+
+	java-pkg_do_write_
+}
+
+# ------------------------------------------------------------------------------
 # @ebuild-function java-pkg_register-environment-variable
 #
 # Register an arbitrary environment variable into package.env. The gjl launcher
@@ -2145,7 +2195,8 @@
 	# Create directory for package.env
 	dodir "${JAVA_PKG_SHAREPATH}"
 	if [[ -n "${JAVA_PKG_CLASSPATH}" || -n "${JAVA_PKG_LIBRARY}" || -f \
-			"${JAVA_PKG_DEPEND_FILE}" ]]; then
+			"${JAVA_PKG_DEPEND_FILE}" || -f \
+			"${JAVA_PKG_OPTIONAL_DEPEND_FILE}" ]]; then
 		# Create package.env
 		(
 			echo "DESCRIPTION=\"${DESCRIPTION}\""
@@ -2155,7 +2206,9 @@
 			[[ -n "${JAVA_PKG_LIBRARY}" ]] && echo "LIBRARY_PATH=\"${JAVA_PKG_LIBRARY}\""
 			[[ -n "${JAVA_PROVIDE}" ]] && echo "PROVIDES=\"${JAVA_PROVIDE}\""
 			[[ -f "${JAVA_PKG_DEPEND_FILE}" ]] \
-				&& echo "DEPEND=\"$(cat	${JAVA_PKG_DEPEND_FILE} | uniq | tr '\n' ':')\""
+				&& echo "DEPEND=\"$(cat "${JAVA_PKG_DEPEND_FILE}" | uniq | tr '\n' ':')\""
+			[[ -f "${JAVA_PKG_OPTIONAL_DEPEND_FILE}" ]] \
+				&& echo "OPTIONAL_DEPEND=\"$(cat "${JAVA_PKG_OPTIONAL_DEPEND_FILE}" | uniq | tr '\n' ':')\""
 			echo "VM=\"$(echo ${RDEPEND} ${DEPEND} | sed -e 's/ /\n/g' | sed -n -e '/virtual\/\(jre\|jdk\)/ { p;q }')\"" # TODO cleanup !
 		) > "${JAVA_PKG_ENV}"
 
@@ -2188,8 +2241,8 @@
 		# TODO try to cleanup if possible
 		sed -e "s/=\":/=\"/" -e "s/:\"$/\"/" -i "${JAVA_PKG_ENV}" || die "Did you forget to call java_init ?"
 	else
-		debug-print "JAVA_PKG_CLASSPATH, JAVA_PKG_LIBRARY or"
-		debug-print "JAVA_PKG_DEPEND_FILE not defined so can't"
+		debug-print "JAVA_PKG_CLASSPATH, JAVA_PKG_LIBRARY, JAVA_PKG_DEPEND_FILE"
+		debug-print "or JAVA_PKG_OPTIONAL_DEPEND_FILE not defined so can't"
 		debug-print "write package.env."
 	fi
 }
@@ -2216,6 +2269,27 @@
 }
 
 # ------------------------------------------------------------------------------
+# @internal-function java-pkg_record-optional-jar_
+#
+# Record an optional dependency to the package.env OPTIONAL_DEPEND line.
+#
+# ------------------------------------------------------------------------------
+JAVA_PKG_OPTIONAL_DEPEND_FILE="${T}/java-pkg-optional-depend"
+
+java-pkg_record-optional-jar_() {
+	debug-print-function ${FUNCNAME} $*
+
+	local pkg=${1} jar=${2} append
+	if [[ -z "${jar}" ]]; then
+		append="${pkg}"
+	else
+		append="$(basename ${jar})@${pkg}"
+	fi
+
+	echo ${append} >> ${JAVA_PKG_OPTIONAL_DEPEND_FILE}
+}
+
+# ------------------------------------------------------------------------------
 # @internal-function java-pkg_append_
 #
 # Appends a value to a variable

Index: Package.py
===================================================================
--- Package.py	(revision 4849)
+++ Package.py	(working copy)
@@ -60,6 +60,16 @@
             return [dep.split("@") for dep in depstr.split(":")]
         else:
             return []
+        
+    def opt_deps(self):
+        """
+        Return all packages this package optionally depends on
+        """
+        depstr = self.query("OPTIONAL_DEPEND")
+        if depstr:
+            return [dep.split("@") for dep in depstr.split(":")]
+        else:
+            return []
 
     def provides(self):
         """
Index: EnvironmentManager.py
===================================================================
--- EnvironmentManager.py	(revision 4849)
+++ EnvironmentManager.py	(working copy)
@@ -263,6 +263,19 @@
     def build_classpath(self, pkgs):
         return self.build_path(pkgs, "CLASSPATH")
 
+    def get_pkg_deps(self, pkg):
+        """
+        Returns list of package's deps and optional deps.
+        Filters out optional deps that are not present.
+        """
+        deps = pkg.deps();
+        for opt_dep in pkg.opt_deps():
+            p = self.get_package(opt_dep[-1])
+            if p:
+                deps.append(opt_dep)
+
+        return deps
+
     def add_dep_classpath(self, pkg, dep, classpath): 
         pkg_cp = pkg.classpath()
         if pkg_cp:
@@ -295,7 +308,7 @@
                 lpath = pkg.query(query)
                 self.add_path_elements(lpath, path)
 
-            for dep in pkg.deps():
+            for dep in self.get_pkg_deps(pkg):
                 p = self.get_package(dep[-1])
 
                 if p:
@@ -344,7 +357,7 @@
 
             self.add_pkg_env_vars(pkg, env)
 
-            for dep in pkg.deps():
+            for dep in pkg.self.get_pkg_deps(pkg):
                 p = self.get_package(dep[-1])
 
                 if p: