Define ECL_HELPER_EXPORT

Defined in File macros.hpp

Define Documentation

ECL_HELPER_EXPORT

Declare public visibility for libraries.

This emits (in a cross platform way) the required symbols for setting whether a function/class should be visible or hidden. Note only does this protect the private parts of your library, but it can also greatly speed up the linking process.

http://gcc.gnu.org/wiki/Visibility

To check what symbols are being exported for a gnu library,

nm -C -D <library>.so

Usage:

Each package needs to create it’s own macro to make use of the macro that cmake defines for library targets:

#ifdef ROS_BUILD_SHARED_LIBS // ros is being built around shared libraries
  #ifdef ecl_common_EXPORTS // we are building a shared lib/dll
    #define ecl_common_PUBLIC ROS_HELPER_EXPORT
  #else // we are using shared lib/dll
    #define ecl_common_PUBLIC ROS_HELPER_IMPORT
  #endif
#else // ros is being built around static libraries
  #define ecl_common_DECL
#endif

And use it alongside class or function definitions:

extern "C" ecl_common_PUBLIC void function(int a);
class ecl_common_PUBLIC SomeClass {
    int c;
    ecl_common_LOCAL void privateMethod();  // Only for use within this DSO
public:
    Person(int _c) : c(_c) { }
    static void foo(int a);
};