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diff --git a/doc/manual.cli b/doc/manual.cli index 0afb97f..7f27ff8 100644 --- a/doc/manual.cli +++ b/doc/manual.cli @@ -246,4 +246,192 @@ A directory target without an explicit target type (for example, \c{foo/}) is treated specially. It enables all the tests at and under its directory. This special treatment can be inhibited by specifying the target type explicitly (for example, \c{dir{foo/\}}). + + +\h1#module-version|Version Module| + +A project can use any version format as long as it meets the package version +requirements. The \c{build2} toolchain also provides additional functionality +for managing projects that conform to the \i{standard version} format. If you +are starting a new project that uses \c{build2}, you are strongly encouraged +to use this versioning scheme since it is based on much thought and +experience. If you decide not to follow this advice, you are essentially on +your own when version management is concerned. + +The \c{build2} standard project version conforms to \l{http://semver.org +Semantic Versioning} and has the following form: + +\ +<major>.<minor>.<patch>[-<prerel>] +\ + +For example: + +\ +1.2.3 +1.2.3-a.1 +1.2.3-b.2 +\ + +The \c{build2} package version that uses the standard project version will +then have the following form (\i{epoch} is the versioning scheme version +and \i{revision} is the package revision): + +\ +[<epoch>~]<major>.<minor>.<patch>[-<prerel>][+<revision>] +\ + +For example: + +\ +1.2.3 +1.2.3+1 +1~1.2.3-a.1+2 +\ + +The \i{major}, \i{minor}, and \i{patch} should be numeric values between 0 and +999 and all three cannot be zero at the same time. For initial development it +is recommended to use 0 for \i{major}, start with version \c{0.1.0}, and change +to \c{1.0.0} once things stabilize. + +In the context of C and C++ (or other compiled languages), you should +increment \i{patch} when making binary-compatible changes, \i{minor} when +making source-compatible changes, and \i{major} when making breaking changes. +While the binary compatibility must be set in stone, the source compatibility +rules can sometimes be bent. For example, you may decide to make a breaking +change in a rarely used interface as part of a minor release. Note also that +in the context of C++ deciding whether a change is binary-compatible is a +non-trivial task. There are resources that list the rules but no automatic +tooling yet. If unsure, increment \i{minor}. + +If present, the \i{prerel} component signifies a pre-release. Two types of +pre-releases are supported by the standard versioning scheme: \i{final} and +\i{snapshot} (non-pre-release versions are naturally always final). For final +pre-releases the \i{prerel} component has the following form: + +\ +(a|b).<num> +\ + +For example: + +\ +1.2.3-a.1 +1.2.3-b.2 +\ + +The letter '\c{a}' signifies an alpha release and '\c{b}' \- beta. The +alpha/beta numbers (\i{num}) should be between 1 and 499. + +Note that there is no support for release candidates. Instead, it is +recommended that you use later-stage beta releases for this purpose (and, if +you wish, call them \"release candidates\" in announcements, etc). + +What version should we use during development? The common approach is to +increment to the next version and use that until the release. This has one +major drawback: if we publish intermediate snapshots (for example, for +testing) they will all be indistinguishable both between each other and, even +worse, from the final release. One way to remedy this is to increment the +pre-release number before each publications. However, unless automated, this +will be burdensome and error prone. Also, there is a real possibility of +running out of version numbers if, for example, we do continuous integration +by testing (and therefore publishing) each commit. + +To address this, the standard versioning scheme supports \i{snapshot +pre-releases} with the \i{prerel} component having the following form: + +\ +(a|b).<num>.<snapsn>[.<snapid>] +\ + +For example: + +\ +1.2.3-a.1.1422564055.340c0a26a5efed1f +\ + +In essence, a snapshot pre-release is after the previous final release but +before the next (\c{a.1} and, perhaps, \c{a.2} in the above example) and +is uniquely identified by the snapshot sequence number (\i{snapsn}) and +snapshot id (\i{snapid}). + +The \i{num} component have the same semantics as in the final pre-releases +except that it can be 0. The \i{snapsn} component should be either the +special value '\c{z}' or a numeric, non-zero value that increases for +each subsequent snapshot. The \i{snapid} component, if present, should +be an alpha-numeric value that uniquely identifies the snapshot. It is +not required for version comparison (\i{snapsn} should be sufficient) +and is included for reference. + +Where do the snapshot sn and id come from? Normally from the version control +system. For example, for \c{git}, \i{snapsn} is the commit date (as UNIX +timestamp) and \i{snapid} is a 16-character abbreviated commit id. As +discussed below, the \c{build2} \c{version} module extracts all this +data automatically. + +The special '\c{z}' \i{snapsn} value identifies a latest or uncommitted +snapshot. It is chosen to be greater than any other possible \i{snapsn} +value and its use is discussed below. + +As an illustration of this approach, let's examine how versions change +during the lifetime of a project: + +\ +0.1.0-a.0.z # development after a.0 +0.1.0-a.1 # pre-release +0.1.0-a.1.z # development after a.1 +0.1.0-a.2 # pre-release +0.1.0-a.2.z # development after a.2 +0.1.0-b.1 # pre-release +0.1.0-b.1.z # development after b.1 +0.1.0 # release +0.1.1-b.0.z # development after b.0 (bugfix) +0.2.0-a.0.z # development after a.0 +0.1.1 # release (bugfix) +1.0.0 # release (jumped straight to 1.0.0) +... +\ + +As shown in the above example, there is nothing wrong with \"jumping\" to a +further version (for example, from alpha to beta, or from beta to release, or +even from alpha to release). We cannot, however, jump backwards (for example, +from beta back to alpha). As a result, a sensible strategy is to start with +\c{a.0} since it can always be upgraded (but not downgrade) at a later stage. + +In terms of the version control system, the recommended workflow is as +follows: The change to the final version should be the last commit in the +(pre-)release. It is also a good idea to tag this commit with the version. A +commit immediately after that should change the version to snapshot +essentially \"opening\" the repository for development. + +The project version without the snapshot part can be represented as a 64-bit +decimal value comparable as integers (for example, in preprocessor +directives). The integer representation has the following form: + +\ +AAABBBCCCDDDE + +AAA - major +BBB - minor +CCC - patch +DDD - alpha / beta (DDD + 500) +E - final (0) / snapshot (1) +\ + +If the \i{DDD} digits are not zero, then they signify a pre-release. In this +case one is subtracted from the \i{AAABBBCCC} value. An alpha number is stored +as is while beta \- incremented by 500. If \i{E} is 1, then this is a snapshot +after \i{DDD}. + +For example: + +\ + AAABBBCCCDDDE +0.1.0 0000010000000 +0.1.2 0000010010000 +1.2.3 0010020030000 +2.2.0-a.1 0020019990010 +3.0.0-b.2 0029999995020 +2.2.0-a.1.z 0020019990011 +\ " |