.. _insensitive-case:

Insensitive case
================

Configuration
-------------

- Introduce the :mconfig:`icase` option name

  - Which is made persistent through the :envvar:`MODULES_ICASE` environment variable
  - Many people asked for separate options as applying an icase approach to a module loading context is not seen desired by everybody whereas it is in an module search context
  - Defined levels of enablement are:

    - ``never``
    - ``search``
    - ``always``

  - icase option will be set by default to

    - ``never`` in v4 not to change existing behaviors
    - ``search`` in v5 as it seems to be a general improvement for everybody

  - A command-line switch :option:`--icase` (short form :option:`-i`) is added

    - Was there in Modules 3 (for search sub-command only)
    - When set, equals to an ``always`` icase mode

- No immediate need for a ``--no-icase`` command-line switch

  - Combining configuration option and ``--icase`` command-line switch seems sufficient

Specification
-------------

- When enabled, match query string in a case insensitive manner

  - query *soFT* returns soft, SOFT, soFT, SOft, sOft and so on

- In case multiple files correspond to the same icase word

  - like *soft*, *soFT*, *SoFt*, *SOFT* filenames
  - query *SOFT* returns *SOFT* (exact match is returned among possibilities)
  - query *SoFt* returns *SoFt* (exact match is returned among possibilities)
  - query *SOft* returns *soft* (highest lexicographically sorted match is returned among possibilities)
  - query *soFt* returns *soft* (highest lexicographically sorted match is returned among possibilities)

- When icase is enabled for search context it applies to

  - module specification passed as argument in following context:

    - :ref:`module_version_specification_to_return_all_matching_modules`

- When icase is enabled for all context it applies to

  - search context like described above
  - module specification passed as argument in following contexts:

    - :ref:`module_version_specification_to_select_one_module`
    - :ref:`module_version_specification_to_check_compatibility`

  - module alias and symbolic version resolution triggered by

    - ``module-info alias``
    - ``module-info version``
    - ``getPathToModule``
    - ``isModuleEvaluated``

  - the gathering of all module alias and symbolic version targeting a given module

    - this is processed by ``getAllModuleResolvedName`` procedure
    - which is called by

      - ``doesLoadingModuleMatchesName``
      - ``cmdModuleLoad``

- Note that whatis specification passed as argument to the ``search`` sub-command is always matched in a case insensitive manner

Corner cases
------------

- When looking for the best match among loaded modules to select one module to unload, lastly loaded module, or firstly loaded module depending on :mconfig:`unload_match_order` configuration, will be returned

  - When insensitive case is enabled, last or first icase match will be returned even if an exact match is present among the loaded module list
  - This behavior has an impact in case multiple available modules correspond to the same insensitive case string

    - For instance *iCaSe* and *IcAsE* modules

- When ``icase`` is enabled on all contexts and multiple directories match same icase module name

  - for instance following modules exist: *ICASE/1.1*, *icase/1.2*, *iCaSe/1.3* and *iCaSe/1.4*
  - a ``module avail -i icase`` will sort *iCaSe/1.4* as the highest entry
  - however a ``module load -i icase`` command will load *icase/1.2*

    - as *icase* directory matches query

  - and also ``module load -i ICase`` command will load *icase/1.2*

    - as no directory *ICase* exists, result is returned from highest directory: *icase*

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