packet lib: packet_base: add a method which makes '_class_prefixes' easy to use

the variable '_class_prefixes' of stringify.StringifyMixin is used to help the method 'from_jsondict()' to create the class instance.
'_class_prefixes' requires a list of the class names.
some classes have another list of the class names already.
this patch adds a method which makes '_class_prefixes' by using the existing list.

before applying this patch:
(e.g. ryu.lib.packet.ipv6)

    # append the name to another list
    @ipv6.register_header_type(inet.IPPROTO_HOPOPTS)
    class hop_opts(opt_header):
    ...

    @ipv6.register_header_type(inet.IPPROTO_DSTOPTS)
    class dst_opts(opt_header):
    ....

    # append the name again
    ipv6._class_prefixes = ['hop_opts', 'dst_opts', ...]

after applying this patch:
(e.g. ryu.lib.packet.ipv6)

    # append the name to another list
    @ipv6.register_header_type(inet.IPPROTO_HOPOPTS)
    class hop_opts(opt_header):
    ...

    @ipv6.register_header_type(inet.IPPROTO_DSTOPTS)
    class dst_opts(opt_header):
    ....

    # create the new list from another list
    ipv6.set_classes(ipv6._IPV6_EXT_HEADER_TYPE)

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 5 insertions, 0 deletions

diff --git a/ryu/lib/stringify.py b/ryu/lib/stringify.py
index 4d56a950..ad771db9 100644
--- a/ryu/lib/stringify.py
+++ b/ryu/lib/stringify.py
@@ -298,6 +298,11 @@ class StringifyMixin(object):
             print "KWARG", kwargs
             raise
 
+    @classmethod
+    def set_classes(cls, registered_dict):
+        cls._class_prefixes.extend([v.__name__ for v in
+                                    registered_dict.values()])
+
 
 def obj_python_attrs(msg_):
     """iterate object attributes for stringify purposes