Added pointer swap macro for callback setters.

src/init.c

@@ -192,8 +192,7 @@ GLFWAPI const char* glfwGetVersionString(void)
 
 GLFWAPI GLFWerrorfun glfwSetErrorCallback(GLFWerrorfun cbfun)
 {
-    GLFWerrorfun previous = _glfwErrorCallback;
+    _GLFW_SWAP_POINTERS(_glfwErrorCallback, cbfun);
-    _glfwErrorCallback = cbfun;
+    return cbfun;
-    return previous;
 }
 

src/input.c

@@ -349,76 +349,52 @@ GLFWAPI void glfwSetCursorPos(GLFWwindow* handle, double xpos, double ypos)
 GLFWAPI GLFWkeyfun glfwSetKeyCallback(GLFWwindow* handle, GLFWkeyfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWkeyfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.key, cbfun);
-    previous = window->callbacks.key;
+    return cbfun;
-    window->callbacks.key = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWcharfun glfwSetCharCallback(GLFWwindow* handle, GLFWcharfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWcharfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.character, cbfun);
-    previous = window->callbacks.character;
+    return cbfun;
-    window->callbacks.character = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWmousebuttonfun glfwSetMouseButtonCallback(GLFWwindow* handle,
                                                       GLFWmousebuttonfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWmousebuttonfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.mouseButton, cbfun);
-    previous = window->callbacks.mouseButton;
+    return cbfun;
-    window->callbacks.mouseButton = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWcursorposfun glfwSetCursorPosCallback(GLFWwindow* handle,
                                                   GLFWcursorposfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWcursorposfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.cursorPos, cbfun);
-    previous = window->callbacks.cursorPos;
+    return cbfun;
-    window->callbacks.cursorPos = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWcursorenterfun glfwSetCursorEnterCallback(GLFWwindow* handle,
                                                       GLFWcursorenterfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWcursorenterfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.cursorEnter, cbfun);
-    previous = window->callbacks.cursorEnter;
+    return cbfun;
-    window->callbacks.cursorEnter = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWscrollfun glfwSetScrollCallback(GLFWwindow* handle,
                                             GLFWscrollfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWscrollfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.scroll, cbfun);
-    previous = window->callbacks.scroll;
+    return cbfun;
-    window->callbacks.scroll = cbfun;
-    return previous;
 }
 

src/internal.h

@@ -120,6 +120,15 @@ typedef struct _GLFWmonitor     _GLFWmonitor;
         return x;                                    \
     }
 
+// Swaps the provided pointers
+#define _GLFW_SWAP_POINTERS(x, y) \
+    {                             \
+        void* t;                  \
+        t = x;                    \
+        x = y;                    \
+        y = t;                    \
+    }
+
 
 //========================================================================
 // Internal types

src/monitor.c

@@ -328,12 +328,9 @@ GLFWAPI const char* glfwGetMonitorName(GLFWmonitor* handle)
 
 GLFWAPI GLFWmonitorfun glfwSetMonitorCallback(GLFWmonitorfun cbfun)
 {
-    GLFWmonitorfun previous;
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(_glfw.monitorCallback, cbfun);
-    previous = _glfw.monitorCallback;
+    return cbfun;
-    _glfw.monitorCallback = cbfun;
-    return previous;
 }
 
 GLFWAPI const GLFWvidmode* glfwGetVideoModes(GLFWmonitor* handle, int* count)

src/window.c

@@ -604,91 +604,63 @@ GLFWAPI GLFWwindowposfun glfwSetWindowPosCallback(GLFWwindow* handle,
                                                   GLFWwindowposfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowposfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.pos, cbfun);
-    previous = window->callbacks.pos;
+    return cbfun;
-    window->callbacks.pos = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWwindowsizefun glfwSetWindowSizeCallback(GLFWwindow* handle,
                                                     GLFWwindowsizefun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowsizefun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.size, cbfun);
-    previous = window->callbacks.size;
+    return cbfun;
-    window->callbacks.size = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWwindowclosefun glfwSetWindowCloseCallback(GLFWwindow* handle,
                                                       GLFWwindowclosefun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowclosefun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.close, cbfun);
-    previous = window->callbacks.close;
+    return cbfun;
-    window->callbacks.close = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWwindowrefreshfun glfwSetWindowRefreshCallback(GLFWwindow* handle,
                                                           GLFWwindowrefreshfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowrefreshfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.refresh, cbfun);
-    previous = window->callbacks.refresh;
+    return cbfun;
-    window->callbacks.refresh = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWwindowfocusfun glfwSetWindowFocusCallback(GLFWwindow* handle,
                                                       GLFWwindowfocusfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowfocusfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.focus, cbfun);
-    previous = window->callbacks.focus;
+    return cbfun;
-    window->callbacks.focus = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWwindowiconifyfun glfwSetWindowIconifyCallback(GLFWwindow* handle,
                                                           GLFWwindowiconifyfun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWwindowiconifyfun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.iconify, cbfun);
-    previous = window->callbacks.iconify;
+    return cbfun;
-    window->callbacks.iconify = cbfun;
-    return previous;
 }
 
 GLFWAPI GLFWframebuffersizefun glfwSetFramebufferSizeCallback(GLFWwindow* handle,
                                                               GLFWframebuffersizefun cbfun)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
-    GLFWframebuffersizefun previous;
-
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
-
+    _GLFW_SWAP_POINTERS(window->callbacks.fbsize, cbfun);
-    previous = window->callbacks.fbsize;
+    return cbfun;
-    window->callbacks.fbsize = cbfun;
-    return previous;
 }
 
 GLFWAPI void glfwPollEvents(void)