gbe_fork/cmake/share/cmake-3.27/Help/command/block.rst

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2023-12-17 02:34:09 +08:00
block
-----
.. versionadded:: 3.25
Evaluate a group of commands with a dedicated variable and/or policy scope.
.. code-block:: cmake
block([SCOPE_FOR [POLICIES] [VARIABLES] ] [PROPAGATE <var-name>...])
<commands>
endblock()
All commands between ``block()`` and the matching :command:`endblock` are
recorded without being invoked. Once the :command:`endblock` is evaluated, the
recorded list of commands is invoked inside the requested scopes, then the
scopes created by the ``block()`` command are removed.
``SCOPE_FOR``
Specify which scopes must be created.
``POLICIES``
Create a new policy scope. This is equivalent to
:command:`cmake_policy(PUSH)`.
``VARIABLES``
Create a new variable scope.
If ``SCOPE_FOR`` is not specified, this is equivalent to:
.. code-block:: cmake
block(SCOPE_FOR VARIABLES POLICIES)
``PROPAGATE``
When a variable scope is created by the :command:`block` command, this
option sets or unsets the specified variables in the parent scope. This is
equivalent to :command:`set(PARENT_SCOPE)` or :command:`unset(PARENT_SCOPE)`
commands.
.. code-block:: cmake
set(var1 "INIT1")
set(var2 "INIT2")
block(PROPAGATE var1 var2)
set(var1 "VALUE1")
unset(var2)
endblock()
# Now var1 holds VALUE1, and var2 is unset
This option is only allowed when a variable scope is created. An error will
be raised in the other cases.
When the ``block()`` is inside a :command:`foreach` or :command:`while`
command, the :command:`break` and :command:`continue` commands can be used
inside the block.
.. code-block:: cmake
while(TRUE)
block()
...
# the break() command will terminate the while() command
break()
endblock()
endwhile()
See Also
^^^^^^^^
* :command:`endblock`
* :command:`return`
* :command:`cmake_policy`