The ability to specify finer constraints on module version has been added to Modules. It enables to filter the module selection to a given version list or range by specifying after the module name a version constraint prefixed by the @ character.

This new feature leverages the version specifier syntax of the Spack package manager as this syntax covers all the needs for a fine-grained selection of module versions. It copes very well with command-line typing, by avoiding characters having a special meaning on shells. Moreover the users of Spack that also are users of Modules may already be familiar with this syntax.

The mechanism introduced here is called advanced module version specifier and it can be activated through the new configuration option advanced_version_spec. Constraints can be expressed to refine the selection of module version to:

• a single version with the @version syntax, for instance [email protected] syntax will select module foo/1.2.3
• a list of versions with the @version1,version2,... syntax, for instance [email protected],1.10 will match modules foo/1.2.3 and foo/1.10
• a range of versions with the @version1:, @:version2 and @version1:version2 syntaxes, for instance [email protected]: will select all versions of module foo greater than or equal to 1.2, foo@:1.3 will select all versions less than or equal to 1.3 and [email protected]:1.3 matches all versions between 1.2 and 1.3 including 1.2 and 1.3 version

This new feature enables for instance to list available versions of module foo higher or equal to 1.2:

$ module config advanced_version_spec 1
$ module av foo
--------------- /path/to/modulefiles ---------------
foo/1.1.1(default)  foo/1.2.1  foo/1.10
foo/1.1.10          foo/1.2.3
$ module av [email protected]:
--------------- /path/to/modulefiles ---------------
foo/1.2.1  foo/1.2.3  foo/1.10

Then choose to load for instance a version higher than or equal to 1.2 and less than or equal to 1.3. Default version is selected if it corresponds to a version included in the range, elsewhere the highest version (also called latest version or implicit default) is selected:

$ module load -v [email protected]:1.3
Loading foo/1.2.3

In case implicit_default option is disabled and no explicit default is found among version specifier matches, an error is returned:

$ module config implicit_default 0
$ module load -v [email protected]:1.3
ERROR: No default version defined for '[email protected]:1.3'

When advanced module version specifier is enabled, it applies everywhere a module could be specified, which means it could be used with any module sub-command or any modulefile Tcl command receiving a module specification as argument. It may help for instance to declare smoother dependencies between modules:

$ module show bar@:2
----------------------------------------------------------
/path/to/modulefiles/bar/2.3:

prereq          [email protected],1.2.1
----------------------------------------------------------
$ module load --auto bar@:2
Loading bar/2.3
  Loading requirement: foo/1.2.1

Advanced specification of single version or list of versions may benefit from the activation of the Extended default mechanism (range of versions natively handles abbreviated versions):

$ module config extended_default 1
$ module load -v [email protected]
Loading foo/1.2.3
$ module unload -v foo @1.2,1.5
Unloading foo/1.2.3

Advanced module version specifier activation can be controlled at configure time with the --enable-advanced-version-spec option. This option could be superseded with the MODULES_ADVANCED_VERSION_SPEC environment variable, which could be set through the config sub-command with the advanced_version_spec option.

This new feature is available in git repository and will be included into the upcoming v4.4 release.