CMake/Help/command/load_cache.rst
Peter Kokot 477737b7bf
load_cache: Add note about export()
The export() command can be a better option when outside project can be
adjusted in such way.
2025-01-28 15:22:29 +01:00

111 lines
3.5 KiB
ReStructuredText

load_cache
----------
Load in the values from another project's ``CMakeCache.txt`` cache file. This
is useful for projects that depend on another project built in a separate
directory tree.
This command has two signatures. The recommended signature is:
.. signature::
load_cache(<build-dir> READ_WITH_PREFIX <prefix> <entry>...)
:target: READ_WITH_PREFIX
Loads the cache file from the specified ``<build-dir>`` build directory and
retrieves the listed cache entries. The retrieved values are stored in local
variables, with their names prefixed by the provided ``<prefix>``. This only
reads the cache values; it does not create or modify entries in the local
project's cache.
``READ_WITH_PREFIX <prefix>``
For each cache ``<entry>``, a local variable is created using the specified
``<prefix>`` followed by the entry name.
This signature can be also used in :option:`cmake -P` script mode.
The following signature of this command is strongly discouraged, but it is
provided for backward compatibility:
.. signature::
load_cache(<build-dir> [EXCLUDE <entry>...] [INCLUDE_INTERNALS <entry>...])
:target: raw
This form loads the cache file from the specified ``<build-dir>`` build
directory and imports all its non-internal cache entries into the local
project's cache as internal cache variables. By default, only non-internal
entries are imported, unless the ``INCLUDE_INTERNALS`` option is used.
The options are:
``EXCLUDE <entry>...``
This option can be used to exclude a given list of non-internal cache
entries when importing values.
``INCLUDE_INTERNALS <entry>...``
This option can be used to provide a list of internal cache entries to
include in addition to the non-internal cache entries.
This signature can be used only in CMake projects. Script mode is not
supported.
.. note::
Instead of loading the outside project's cache file and manually accessing
variables, a more robust and convenient approach is to use the
:command:`export` command in the outside project, when available. This allows
the project to provide its targets, configuration, or features in a
structured and maintainable way, making integration simpler and less
error-prone.
Examples
^^^^^^^^
Reading specific cache variables from another project and storing them as local
variables:
.. code-block:: cmake
load_cache(
path/to/other-project/build-dir
READ_WITH_PREFIX prefix_
OTHER_PROJECT_CACHE_VAR_1
OTHER_PROJECT_CACHE_VAR_2
)
message(STATUS "${prefix_OTHER_PROJECT_CACHE_VAR_1")
message(STATUS "${prefix_OTHER_PROJECT_CACHE_VAR_2")
# Outputs:
# -- some-value...
# -- another-value...
Reading all non-internal cache entries from another project and storing them as
internal cache variables using the obsolete signature:
.. code-block:: cmake
load_cache(path/to/other-project/build-dir)
message(STATUS "${OTHER_PROJECT_CACHE_VAR_1")
message(STATUS "${OTHER_PROJECT_CACHE_VAR_2")
# Outputs:
# -- some-value...
# -- another-value...
Excluding specific non-internal cache entries and including internal ones using
the obsolete signature:
.. code-block:: cmake
load_cache(
path/to/other-project/build-dir
EXCLUDE OTHER_PROJECT_CACHE_VAR_2
INCLUDE_INTERNALS OTHER_PROJECT_INTERNAL_CACHE_VAR
)
message(STATUS "${OTHER_PROJECT_CACHE_VAR_1")
message(STATUS "${OTHER_PROJECT_CACHE_VAR_2")
message(STATUS "${OTHER_PROJECT_INTERNAL_CACHE_VAR}")
# Outputs:
# -- some-value...
# --
# -- some-internal-value...