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authorWenchao Xia <wenchaoqemu@gmail.com>2014-03-04 18:44:39 -0800
committerLuiz Capitulino <lcapitulino@redhat.com>2014-03-11 09:07:42 -0400
commit5223070c47c6fc35ee000b2392ae76d9fab54f16 (patch)
tree52a971bbbc5db95b1ebaa064483eeb6ee54ecaeb /docs
parent59ca664ef86c8a9078157336b566e832fc5466e2 (diff)
qapi script: do not allow string discriminator
Since enum based discriminators provide better type-safety and ensure that future qapi additions do not forget to adjust dependent unions, forbid using string as discriminator from now on. Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/qapi-code-gen.txt5
1 files changed, 1 insertions, 4 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index a2e7921601..d78921f875 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -123,10 +123,7 @@ And it looks like this on the wire:
Flat union types avoid the nesting on the wire. They are used whenever a
specific field of the base type is declared as the discriminator ('type' is
-then no longer generated). The discriminator can be a string field or a
-predefined enum field. If it is a string field, a hidden enum type will be
-generated as "[UNION_NAME]Kind". If it is an enum field, a compile time check
-will be done to verify the correctness. It is recommended to use an enum field.
+then no longer generated). The discriminator must be of enumeration type.
The above example can then be modified as follows:
{ 'enum': 'BlockdevDriver', 'data': [ 'raw', 'qcow2' ] }