Hide visibility of sinqController classes

src/msgPrintControl.h

@@ -10,12 +10,27 @@
 #include <string>
 #include <unordered_map>
 
+/*
+The macro "HIDDEN" hides the symbol of the annotated class / function. This is
+useful to avoid symbol clashes when loading multiple shared libraries in a
+single IOC. To override the hiding, add `-DHIDDEN= ` to your compiler
+flags (in this case, the symbols will be exported with their default
+visibility).
+*/
+#ifndef HIDDEN
+#if defined(_WIN32) || defined(__CYGWIN__)
+#define HIDDEN
+#else
+#define HIDDEN __attribute__((visibility("hidden")))
+#endif
+#endif
+
 /**
  * @brief Class to identify a message print location. See the docstring of
  * `msgPrintControl` on how to use this key.
  *
  */
-class msgPrintControlKey {
+class HIDDEN msgPrintControlKey {
   public:
     std::string controller_;
 
@@ -82,7 +97,7 @@ template <> struct hash<msgPrintControlKey> {
  * }
  * ```
  */
-class msgPrintControl {
+class HIDDEN msgPrintControl {
   public:
     /**
      * @brief Destroy the msgPrintControl object