Add documentation about the prefix and no_deprecated options.

Modules/GenerateExportHeader.cmake

@@ -15,6 +15,9 @@
 #             [DEPRECATED_MACRO_NAME <deprecated_macro_name>]
 #             [NO_EXPORT_MACRO_NAME <no_export_macro_name>]
 #             [STATIC_DEFINE <static_define>]
+#             [NO_DEPRECATED_MACRO_NAME <no_deprecated_macro_name>]
+#             [DEFINE_NO_DEPRECATED]
+#             [PREFIX_NAME <prefix_name>]
 # )
 #
 # ADD_COMPILER_EXPORT_FLAGS( [FATAL_WARNINGS] )
@@ -97,6 +100,45 @@
 #   set_target_properties(static_variant PROPERTIES COMPILE_FLAGS -DLIBSHARED_AND_STATIC_STATIC_DEFINE)
 #
 # This will cause the export macros to expand to nothing when building the static library.
+#
+# If DEFINE_NO_DEPRECATED is specified, then a macro ${BASE_NAME}_NO_DEPRECATED will be defined
+# This macro can be used to remove deprecated code from preprocessor output.
+#
+#   option(EXCLUDE_DEPRECATED "Exclude deprecated parts of the library" FALSE)
+#
+#   if (EXCLUDE_DEPRECATED)
+#     set(NO_BUILD_DEPRECATED DEFINE_NO_DEPRECATED)
+#   endif()
+#
+#   generate_export_header(somelib ${NO_BUILD_DEPRECATED})
+#
+# And then in somelib:
+#
+#   \code
+#   class SOMELIB_EXPORT SomeClass
+#   {
+#   public:
+#   #ifndef SOMELIB_NO_DEPRECATED
+#     SOMELIB_DEPRECATED void oldMethod();
+#   #endif
+#   };
+#
+#   // ...
+#
+#   #ifndef SOMELIB_NO_DEPRECATED
+#   void SomeClass::oldMethod() {  }
+#   #endif
+#
+#   \endcode
+#
+# If PREFIX_NAME is specified, the argument will be used as a prefix to all
+# generated macros.
+#
+# For example:
+#
+#   generate_export_header(somelib PREFIX_NAME VTK_)
+#
+# Generates the macros VTK_SOMELIB_EXPORT etc.
 
 
 #=============================================================================