Generic API interface

CMakeLists.txt

@@ -13,9 +13,9 @@ add_library(Core SHARED ${CORE_SOURCES})
 add_library(App1 SHARED ${APP1_SOURCES})
 add_library(App2 SHARED ${APP2_SOURCES})
 
-set_target_properties(Core PROPERTIES COMPILE_DEFINITIONS "EXPORT_CORE=1")
-set_target_properties(App1 PROPERTIES COMPILE_DEFINITIONS "EXPORT_APP1=1")
-set_target_properties(App2 PROPERTIES COMPILE_DEFINITIONS "EXPORT_APP2=1")
+set_target_properties(Core PROPERTIES COMPILE_DEFINITIONS "CORE=_,_")
+set_target_properties(App1 PROPERTIES COMPILE_DEFINITIONS "APP1=_,_")
+set_target_properties(App2 PROPERTIES COMPILE_DEFINITIONS "APP2=_,_")
 
 target_link_libraries(App1 Core)
 target_link_libraries(App2 App1 Core)

app1.cpp

@@ -3,7 +3,7 @@
 
 namespace Kratos {
 
-  KRATOS_CREATE_VARIABLE(int, APP1_INT, 1)
+  KRATOS_CREATE_VARIABLE(API(APP1), int, APP1_INT, 1)
 
   int app1_function() {
     return APP1_INT;

app1.hpp

@@ -1,18 +1,11 @@
 #include <iostream>
 #include "define.hpp"
-
-#ifdef EXPORT_APP1
-#undef  API
-#define API API_EXPORT
-#else
-#undef  API
-#define API API_IMPORT
-#endif
+#include "core.hpp"
 
 namespace Kratos {
 
-  KRATOS_DEFINE_VARIABLE(int, APP1_INT)
+  KRATOS_DEFINE_VARIABLE(API(APP1), int, APP1_INT)
 
-  API int app1_function();
-  API void test_app1();
+  API(APP1) int app1_function();
+  API(APP1) void test_app1();
 }

app2.cpp

@@ -4,7 +4,7 @@
 
 namespace Kratos {
 
-  KRATOS_CREATE_VARIABLE(int, APP2_INT, 2)
+  KRATOS_CREATE_VARIABLE(API(APP2), int, APP2_INT, 2)
 
   int app2_function() {
     return APP2_INT;

app2.hpp

@@ -1,18 +1,10 @@
 #include <iostream>
 #include "define.hpp"
 
-#ifdef EXPORT_APP2
-#undef  API
-#define API API_EXPORT
-#else
-#undef  API
-#define API API_IMPORT
-#endif
-
 namespace Kratos {
 
-  KRATOS_DEFINE_VARIABLE(int, APP2_INT)
+  KRATOS_DEFINE_VARIABLE(API(APP2), int, APP2_INT)
 
-  API int app2_function();
-  API void test_app2();
+  API(APP2) int app2_function();
+  API(APP2) void test_app2();
 }

core.cpp

@@ -1,9 +1,8 @@
-// This file is the main application that uses DLL
 #include "core.hpp"
 
 namespace Kratos {
 
-  KRATOS_CREATE_VARIABLE(int, CORE_INT, 0)
+  KRATOS_CREATE_VARIABLE(API(CORE), int, CORE_INT, 0)
 
   int core_function() {
     return CORE_INT;

core.hpp

@@ -1,18 +1,10 @@
 #include <iostream>
 #include "define.hpp"
 
-#ifdef EXPORT_CORE
-#undef  API
-#define API API_EXPORT
-#else
-#undef  API
-#define API API_IMPORT
-#endif
-
 namespace Kratos {
 
-  KRATOS_DEFINE_VARIABLE(int, CORE_INT)
+  KRATOS_DEFINE_VARIABLE(API(CORE), int, CORE_INT)
 
-  API int core_function();
-  API void test_core();
+  API(CORE) int core_function();
+  API(CORE) void test_core();
 }

define.hpp

@@ -9,9 +9,16 @@
   #define API_IMPORT __attribute__((visibility("default")))
 #endif
 
-#define KRATOS_DEFINE_VARIABLE(type, name)      API extern type name;
+// This fixes MSVC not expanding __VA_ARGS__ as defined in the C99 standard
+#define EXPAND(A) A
 
-#define KRATOS_CREATE_VARIABLE(type, name, val) API type name = val;
+// Random macro magic
+#define API_CALL(x,T1,T2,T3,...) T3
+#define API(...) EXPAND(API_CALL(,##__VA_ARGS__,API_EXPORT,API_IMPORT))
+
+#define KRATOS_DEFINE_VARIABLE(api, type, name)      api extern type name;
+
+#define KRATOS_CREATE_VARIABLE(api, type, name, val) api type name = val;
 #define KRATOS_REGISTER_VARIABLE(var) // NOT USED HERE
 
 #endif