python-single-r1.eclass: Document new pattern support

eclass/python-single-r1.eclass

@@ -271,8 +271,11 @@ if [[ ! ${_PYTHON_SINGLE_R1} ]]; then
 # are both in PYTHON_COMPAT and match any of the patterns passed
 # as parameters to the function.
 #
-# Remember to escape or quote the patterns to prevent shell filename
-# expansion.
+# The patterns can be either fnmatch-style patterns (matched via bash
+# == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
+# appropriately all enabled Python 2/3 implementations (alike
+# python_is_python3). Remember to escape or quote the fnmatch patterns
+# to prevent accidental shell filename expansion.
 #
 # When all implementations are requested, please use ${PYTHON_USEDEP}
 # instead. Please also remember to set an appropriate REQUIRED_USE
@@ -315,6 +318,12 @@ python_gen_usedep() {
 # are both in PYTHON_COMPAT and match any of the patterns passed
 # as parameters to the function.
 #
+# The patterns can be either fnmatch-style patterns (matched via bash
+# == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
+# appropriately all enabled Python 2/3 implementations (alike
+# python_is_python3). Remember to escape or quote the fnmatch patterns
+# to prevent accidental shell filename expansion.
+#
 # Example:
 # @CODE
 # PYTHON_COMPAT=( python{2_7,3_4} )
@@ -352,6 +361,12 @@ python_gen_useflags() {
 # of Python implementations which are both in PYTHON_COMPAT and match
 # any of the patterns passed as the remaining parameters.
 #
+# The patterns can be either fnmatch-style patterns (matched via bash
+# == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
+# appropriately all enabled Python 2/3 implementations (alike
+# python_is_python3). Remember to escape or quote the fnmatch patterns
+# to prevent accidental shell filename expansion.
+#
 # In order to enforce USE constraints on the packages, verbatim
 # '${PYTHON_USEDEP}' (quoted!) may be placed in the dependency
 # specification. It will get expanded within the function into a proper
@@ -411,6 +426,12 @@ python_gen_cond_dep() {
 # patterns are passed, the output dependencies will be generated only
 # for the implementations matching them.
 #
+# The patterns can be either fnmatch-style patterns (matched via bash
+# == operator against PYTHON_COMPAT values) or '-2' / '-3' to indicate
+# appropriately all enabled Python 2/3 implementations (alike
+# python_is_python3). Remember to escape or quote the fnmatch patterns
+# to prevent accidental shell filename expansion.
+#
 # Use this function when you need to request different USE flags
 # on the Python interpreter depending on package's USE flags. If you
 # only need a single set of interpreter USE flags, just set