On 03/06/2017 05:04 AM, Daniel P. Berrange wrote:
On Mon, Mar 06, 2017 at 10:21:28AM +0100, Bjoern Walk wrote:
Daniel P. Berrange <berrange@redhat.com> [2017-03-03, 10:50AM +0100]:
This documents the preferred conventions for naming files, structs, enums, typedefs and functions.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com> --- HACKING | 71 ++++++++++++++++++++++++++++++++++++++++++++ docs/hacking.html.in | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++ docs/hacking2.xsl | 4 +++ 3 files changed, 158 insertions(+)
diff --git a/HACKING b/HACKING index fff003b..16be5cf 100644 --- a/HACKING +++ b/HACKING @@ -239,6 +239,77 @@ on the subject, on Richard Jones' guide to working with open source projects <http://people.redhat.com/rjones/how-to-supply-code-to-open-source-projects/>.
+Naming conventions +================== +When reading libvirt code, a number of different naming conventions will be +evident due to various changes in thinking over the course of the project's +lifetime. The conventions documented below should be followed when creating +any entirely new files in libvirt. When working on existing files, while it is +desirable to apply these conventions, keeping a consistent style with existing +code in that particular file is generally more important. The overall guiding +rule is that every file, enum, struct, function, and typedef name must have a +'vir' or 'VIR' prefix. All local scope variable names are exempt, and global +variables are exempt, unless exported in a header file. + +*File names* + +File naming varies depending on the subdirectory. The preferred style is to +have a 'vir' prefix, followed by a name which matches the name of the +functions / objects inside the file. For example, a file containing an object +'virHashtable' is stored in files 'virhashtable.c' and 'virhashtable.h'. +Sometimes, methods which would otherwise be declared 'static' need to be +exported for use by a test suite. For this purpose a second header file should +be added with a suffix of 'priv'. e.g. 'virhashtablepriv.h'. USe of +underscores in file names is discouraged when using the 'vir' prefix style. +The 'vir' prefix naming applies to src/util, src/rpc and tests/ directories. +Most other directories do not follow this convention. + + + +*Enum type & field names* + +All enums should have a 'vir' prefix in their typedef name, and each following +word should have its first letter in uppercase. The enum name should match the +typedef name with a leading underscore. The enum member names should be in all +uppercase, and use an underscore to separate each word. The enum member name +prefix should match the enum typedef name. + + typedef enum _virSocketType virSocketType; + enum _virSocketType { + VIR_SOCKET_TYPE_IPV4, + VIR_SOCKET_TYPE_IPV6, + }; + + +*Struct type names* + +All structs should have a 'vir' prefix in their typedef name, and each +following word should have its first letter in uppercase. The struct name +should be the same as the typedef name with a leading underscore. A second +typedef should be given for a pointer to the struct with a 'Ptr' suffix. + + typedef struct _virHashTable virHashTable; + typedef virHashTable *virHashTablePtr; + struct _virHashTable { + ... + }; + I personally would prefer this style:
typedef struct _virHashTable { ... } virHashTable, *virHashTablePtr; This is done for example in src/conf/device_conf.h. Subjectively, it is much easier to read, but objectively, it is more concise and enhances discoverability. For example, in src/conf/domain_conf.h the typedef are at the beginning of the file separated from the definition of the struct. If I want to look up a virDomainDiskDefPtr it requires two jumps. We should change device_conf.h really - it is different from pretty much everywhere else in the libvirt codebase.
There are others too. I've always disliked the separate typedefs and extra _virBlah struct name, so quite awhile back I posted some patches that used the more compact style in new struct definitions as a way of suggesting that we use that instead, and they passed review. So I did several more that way, and those passed as well (although I do remember one dissenting opinion for one patch). But if we're going to formalize struct definitions in a coding standards document, then I'm willing to throw in the towel - to avoid leading unsuspecting copy-pasters in the wrong direction, I just sent a patch that changes all "compact format" struct definitions to the more verbose format in the document.