CMake/Help/variable/CACHE.rst
Joachim Wuttke (l) 860338491e Help: Describe $CACHE and $ENV as operators
This resolves issue #18514

Also add a cross-reference to if(DEFINED ENV{var}).
2018-11-08 20:33:13 +01:00

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CACHE
-----
Operator to read cache variables.
Use the syntax ``$CACHE{VAR}`` to read cache entry ``VAR``.
See the :ref:`cmake-language(7) variables <CMake Language Variables>`
documentation for more complete documentation of the interaction of
normal variables and cache entries.
When evaluating :ref:`Variable References` of the form ``${VAR}``,
CMake first searches for a normal variable with that name, and if not
found CMake will search for a cache entry with that name.
The ``$CACHE{VAR}`` syntax can be used to do direct cache lookup and
ignore any existing normal variable.
See the :command:`set` and :command:`unset` commands to see how to
write or remove cache variables.