| DEFINE_SYMBOL |
| ------------- |
| |
| Define a symbol when compiling this target's sources. |
| |
| ``DEFINE_SYMBOL`` sets the name of the preprocessor symbol defined when |
| compiling sources in a shared library. If not set here then it is set |
| to ``target_EXPORTS`` by default (with some substitutions if the target is |
| not a valid C identifier). This is useful for headers to know whether |
| they are being included from inside their library or outside to |
| properly setup dllexport/dllimport decorations on Windows. |
| |
| On POSIX platforms, this can optionally be used to control the visibility |
| of symbols. |
| |
| CMake provides support for such decorations with the :module:`GenerateExportHeader` |
| module. |
