diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/qapi-code-gen.txt | 61 |
1 files changed, 39 insertions, 22 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt index 6746c1052c..9514d936ad 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 |