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Diffstat (limited to 'docs/qapi-code-gen.txt')
| -rw-r--r-- | docs/qapi-code-gen.txt | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt index 0728f36c65..a2e7921601 100644 --- a/docs/qapi-code-gen.txt +++ b/docs/qapi-code-gen.txt @@ -123,11 +123,15 @@ 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 must always be a string field. +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. The above example can then be modified as follows: + { 'enum': 'BlockdevDriver', 'data': [ 'raw', 'qcow2' ] } { 'type': 'BlockdevCommonOptions', - 'data': { 'driver': 'str', 'readonly': 'bool' } } + 'data': { 'driver': 'BlockdevDriver', 'readonly': 'bool' } } { 'union': 'BlockdevOptions', 'base': 'BlockdevCommonOptions', 'discriminator': 'driver', |