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47 lines
1.8 KiB
47 lines
1.8 KiB
7 years ago
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include_guard
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-------------
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Provides an include guard for the file currently being processed by CMake.
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::
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include_guard([DIRECTORY|GLOBAL])
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Sets up an include guard for the current CMake file (see the
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:variable:`CMAKE_CURRENT_LIST_FILE` variable documentation).
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CMake will end its processing of the current file at the location of the
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:command:`include_guard` command if the current file has already been
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processed for the applicable scope (see below). This provides functionality
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similar to the include guards commonly used in source headers or to the
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``#pragma once`` directive. If the current file has been processed previously
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for the applicable scope, the effect is as though :command:`return` had been
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called. Do not call this command from inside a function being defined within
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the current file.
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An optional argument specifying the scope of the guard may be provided.
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Possible values for the option are:
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``DIRECTORY``
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The include guard applies within the current directory and below. The file
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will only be included once within this directory scope, but may be included
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again by other files outside of this directory (i.e. a parent directory or
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another directory not pulled in by :command:`add_subdirectory` or
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:command:`include` from the current file or its children).
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``GLOBAL``
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The include guard applies globally to the whole build. The current file
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will only be included once regardless of the scope.
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If no arguments given, ``include_guard`` has the same scope as a variable,
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meaning that the include guard effect is isolated by the most recent
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function scope or current directory if no inner function scopes exist.
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In this case the command behavior is the same as:
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.. code-block:: cmake
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if(__CURRENT_FILE_VAR__)
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return()
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endif()
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set(__CURRENT_FILE_VAR__ TRUE)
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