Control mode behaviors

• Modulefile commands that modify environment variables applies

  • a behavior when modulefile is loaded

  • and another behavior when modulefile is unloaded

• Depending on the situation, it seems interesting to apply a different behavior when modulefile is unloaded:

  • restore value unset at load time, either:

    • append-on-unload

    • prepend-on-unload

  • remove value from list: remove-on-unload

  • unset full variable value: unset-on-unload

  • set another value, either:

    • append-on-unload

    • prepend-on-unload

    • set-on-unload (for non-path-like variable)

  • do nothing: noop-on-unload

• Also when modulefile loads sometimes it may be interesting to apply a slightly different behavior depending on the situation:

  • set value only if variable is undefined: set-if-undef

• Concerned modulefile commands:

  • module use

  • module unuse

  • setenv

  • unsetenv

  • append-path

  • prepend-path

  • remove-path

• Only applies when the above commands are called from a modulefile (as some of these commands can also act as module sub-commands)

Unload behavior

• Unload behavior of concerned modulefile commands:

  Command	Default unload behavior	Specific unload behavior	Alternative behaviors to add
  module use	remove-on-unload	n/a
  module unuse	remove-on-unload	n/a	append-on-unload, prepend-on-unload, noop-on-unload
  setenv	unset-on-unload	n/a
  unsetenv	noop-on-unload	set-on-unload (when 2nd argument is provided)	unset-on-unload
  append-path	remove-on-unload	n/a
  prepend-path	remove-on-unload	n/a
  remove-path	noop-on-unload	n/a	remove-on-unload, append-on-unload, prepend-on-unload

• When either restoring or setting other value for path-like modulefile commands, it is needed to know if the value should be appended or prepended.

• Either restoring or setting other value result in the same behavior name

  • append-on-unload and prepend-on-unload

  • position of the option will determine if the values to set are:

    • those unset at load time: when option is placed prior value list

    • a different list of value: when option is placed after value list to unset at load time and another value list is defined after option

• The set-on-unload behavior is only useful for modulefile commands which unset value on load mode, as commands that set value on load mode mainly need to unset the value set.

• Default unload behavior of module unuse, unsetenv and remove-path commands can also be set as an option in their argument list. Helps to dynamically choose the behavior to apply, which could be the default behavior.

Load behavior

• Load behavior of concerned modulefile commands:

  Command	Default load behavior	Alternative behaviors to add
  module use	set-on-load
  module unuse	remove-on-load
  setenv	set-on-load	set-if-undef
  unsetenv	unset-on-load
  append-path	add-on-load
  prepend-path	add-on-load
  remove-path	remove-on-load

Modulefile command options

• Alternative behaviors could be specified by setting the associated option over the modulefile command:

  • --remove-on-unload

  • --append-on-unload

  • --prepend-on-unload

  • --noop-on-unload

  • --unset-on-unload

  • --set-if-undef

• The --append-on-unload and --prepend-on-unload options either:

  • restore the value list removed at load time if placed prior this value list

  • set a different value list if a different list of value is specified after option (all the values set after the option are considered element to add to the path-like variable)

  • both options also accept to be set prior or right after variable name or even right at the end of argument list to restore value list removed at load time

• The --set-if-undef option does not change the behavior of setenv when modulefile is unloaded: environment variable will be unset whether the option is set or not.

• The --remove-on-unload option can be set anywhere in argument list

• The --remove-on-unload, --append-on-unload and --prepend-on-unload options cannot be mixed with the --index option of remove-path sub-command.

• The --append-on-unload, --prepend-on-unload options cannot be mixed with the --glob option of remove-path sub-command.

• The --remove-on-unload, --append-on-unload, --prepend-on-unload and --noop-on-unload options:

  • can be placed at different positions in argument list to limit error cases

  • if multiple options of this kind are defined in argument list, the one defined at the most right is retained

Misc

• FUTURE: what is applied to:

  • module use may also be interesting for module load

  • module unuse may also be interesting for module unload