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8.3 Version Numbering

As Clon evolves over time, you might one day feel the need for conditionalizing your code on the version of the library. While the end-user of your application has limited means to access the current version number of Clon (see Clonification in The Clon End-User Manual and the built-in option --clon-version), you, the application programmer and Clon user, have a finer grained access to it.

The first thing you can do to access the current version number of Clon is use the version function (this is in fact the function bound to the --clon-version option).

Function: version &optional (TYPE :number) ¶

Return the current version number of Clon. TYPE can be one of :number, :short or :long. For :number, the returned value is a fixnum. Otherwise, it is a string.

A Clon version is characterized by 4 elements as described below.

• A major version number stored in the parameter *release-major-level*.
• A minor version number, stored in the parameter *release-minor-level*.
• A release status stored in the parameter *release-status*. The status of a release can be :alpha, :beta, :rc (standing for “release candidate”) or :patchlevel. These are in effect 4 levels of expected stability.
• A status-specific version number stored in the parameter *release-status-level*. Status levels start at 1 (alpha 1, beta 1 and release candidate 1) except for stable versions, in which case patch levels start at 0 (e.g. 2.4.0).

In addition to that, each version of Clon (in the sense major.minor, regardless of the status) has a name, stored in the parameter *release-name*. The general naming theme for Clon is “Great Jazz Musicians”. Anyone daring to mention Kenny G at that point will be shot on sight.

Here is how the version function computes its value.

• A version :number is computed as major . 10000 + minor . 100 + patchlevel, effectively leaving two digits for each level. Note that alpha, beta and release candidate status are ignored in version numbers (this is as if the corresponding status level was considered to be always 0). Only stable releases have their level taken into account.
• A :short version will appear like this for unstable releases: 1.3a4, 2.5b8 or 4.2rc1. Remember that alpha, beta or release candidate levels start at 1. Patchlevels for stable releases start at 0 but 0 is ignored in the output. So for instance, version 4.3.2 will appear as-is, while version 1.3.0 will appear as just 1.3.
• A :long version is expanded from the short one, and includes the release name. For instance, 1.3 alpha 4 "Bill Evans", 2.5 beta 8 "Scott Henderson", 4.2 release candidate 1 "Herbie Hancock" or 4.3.2 "Chick Corea". As for the short version, a patchlevel of 0 is ignored in the output: 1.3 "Bill Evans".

Incidentally, but you will probably never need to use it, Clon also exports a variable named *copyright-years*, which, as its name suggests, is a string denoting the copyright years for the whole project.