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authorMarkus Armbruster <armbru@redhat.com>2017-02-28 22:27:09 +0100
committerMarkus Armbruster <armbru@redhat.com>2017-03-07 16:07:48 +0100
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tree179707e298d42a4c78d766648962d2e893929fad /docs
parent31478f26ab4ed82d35b763bbf259810d0c8b44e1 (diff)
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docs/qapi-code-gen.txt: Clarify naming rules
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <1488317230-26248-24-git-send-email-armbru@redhat.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/qapi-code-gen.txt61
1 files changed, 39 insertions, 22 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 6746c10..9514d93 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -216,33 +216,38 @@ single-dimension array of that type; multi-dimension arrays are not
directly supported (although an array of a complex struct that
contains an array member is possible).
+All names must begin with a letter, and contain only ASCII letters,
+digits, hyphen, and underscore. There are two exceptions: enum values
+may start with a digit, and names that are downstream extensions (see
+section Downstream extensions) start with underscore.
+
+Names beginning with 'q_' are reserved for the generator, which uses
+them for munging QMP names that resemble C keywords or other
+problematic strings. For example, a member named "default" in qapi
+becomes "q_default" in the generated C code.
+
Types, commands, and events share a common namespace. Therefore,
generally speaking, type definitions should always use CamelCase for
-user-defined type names, while built-in types are lowercase. Type
-definitions should not end in 'Kind', as this namespace is used for
-creating implicit C enums for visiting union types, or in 'List', as
-this namespace is used for creating array types. Command names,
-and member names within a type, should be all lower case with words
-separated by a hyphen. However, some existing older commands and
-complex types use underscore; when extending such expressions,
-consistency is preferred over blindly avoiding underscore. Event
-names should be ALL_CAPS with words separated by underscore. Member
-names cannot start with 'has-' or 'has_', as this is reserved for
-tracking optional members.
+user-defined type names, while built-in types are lowercase.
+
+Type names ending with 'Kind' or 'List' are reserved for the
+generator, which uses them for implicit union enums and array types,
+respectively.
+
+Command names, and member names within a type, should be all lower
+case with words separated by a hyphen. However, some existing older
+commands and complex types use underscore; when extending such
+expressions, consistency is preferred over blindly avoiding
+underscore.
+
+Event names should be ALL_CAPS with words separated by underscore.
+
+Member names starting with 'has-' or 'has_' are reserved for the
+generator, which uses them for tracking optional members.
Any name (command, event, type, member, or enum value) beginning with
"x-" is marked experimental, and may be withdrawn or changed
-incompatibly in a future release. All names must begin with a letter,
-and contain only ASCII letters, digits, dash, and underscore. There
-are two exceptions: enum values may start with a digit, and any
-extensions added by downstream vendors should start with a prefix
-matching "__RFQDN_" (for the reverse-fully-qualified-domain-name of
-the vendor), even if the rest of the name uses dash (example:
-__com.redhat_drive-mirror). Names beginning with 'q_' are reserved
-for the generator: QMP names that resemble C keywords or other
-problematic strings will be munged in C to use this prefix. For
-example, a member named "default" in qapi becomes "q_default" in the
-generated C code.
+incompatibly in a future release.
In the rest of this document, usage lines are given for each
expression type, with literal strings written in lower case and
@@ -643,6 +648,18 @@ any non-empty complex type (struct, union, or alternate), and a
pointer to that QAPI type is passed as a single argument.
+=== Downstream extensions ===
+
+QAPI schema names that are externally visible, say in the Client JSON
+Protocol, need to be managed with care. Names starting with a
+downstream prefix of the form __RFQDN_ are reserved for the downstream
+who controls the valid, reverse fully qualified domain name RFQDN.
+RFQDN may only contain ASCII letters, digits, hyphen and period.
+
+Example: Red Hat, Inc. controls redhat.com, and may therefore add a
+downstream command __com.redhat_drive-mirror.
+
+
== Client JSON Protocol introspection ==
Clients of a Client JSON Protocol commonly need to figure out what