Refactor the dart api a bit:

runtime/bin/main.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 
@@ skipping 92 matching lines @@
       pprof_file->WriteFully(buffer, buffer_size);
     }
     delete pprof_file;  // Closes the file.
     Dart_ExitScope();
   }
 }
 
 
 static void* MainIsolateInitCallback(void* data) {
   const char* script_name = reinterpret_cast<const char*>(data);
-  Dart_Result result;
+  Dart_Handle library;
   Dart_EnterScope();
 
   // Load the specified script.
-  result = LoadScript(script_name);
-  if (!Dart_IsValidResult(result)) {
-    const char* err_msg = Dart_GetErrorCString(result);
+  library = LoadScript(script_name);
+  if (!Dart_IsValid(library)) {
+    const char* err_msg = Dart_GetError(library);
     fprintf(stderr, "Errors encountered while loading script: %s\n", err_msg);
     Dart_ExitScope();
     exit(255);
   }
 
-  Dart_Handle library = Dart_GetResult(result);
   if (!Dart_IsLibrary(library)) {
     fprintf(stderr,
             "Expected a library when loading script: %s",
             script_name);
     Dart_ExitScope();
     exit(255);
   }
   Builtin_ImportLibrary(library);
   // Setup the native resolver for built in library functions.
   Builtin_SetNativeResolver();
@@ skipping 13 matching lines @@
   for (int i = 0; i < options.count(); i++) {
     if (strcmp(options.GetArgument(i), "--compile_all") == 0) {
       return true;
     }
   }
   return false;
 }
 
 
 static void PrintObject(FILE* out, Dart_Handle object) {
-  Dart_Result result = Dart_ObjectToString(object);
-  if (Dart_IsValidResult(result)) {
-    Dart_Handle string = Dart_GetResult(result);
-    PrintString(out, string);
+  Dart_Handle result = Dart_ObjectToString(object);
+  if (Dart_IsValid(result)) {
+    PrintString(out, result);
   } else {
-    fprintf(out, "%s\n", Dart_GetErrorCString(result));
+    fprintf(out, "%s\n", Dart_GetError(result));
   }
 }
 
 
 int main(int argc, char** argv) {
   char* script_name;
   CommandLineOptions vm_options(argc);
   CommandLineOptions dart_options(argc);
 
   // Parse command line arguments.
@@ skipping 22 matching lines @@
                                             canonical_script_name);
   if (isolate == NULL) {
     free(canonical_script_name);
     return 255;
   }
 
   Dart_EnterScope();
   // TODO(asiva): Create a dart options object that can be accessed from
   // dart code.
   if (HasCompileAll(vm_options)) {
-    Dart_Result result = Dart_CompileAll();
-    if (!Dart_IsValidResult(result)) {
-      fprintf(stderr, "%s\n", Dart_GetErrorCString(result));
+    Dart_Handle result = Dart_CompileAll();
+    if (!Dart_IsValid(result)) {
+      fprintf(stderr, "%s\n", Dart_GetError(result));
       Dart_ExitScope();
       Dart_ShutdownIsolate();
       free(canonical_script_name);
       return 255;  // Indicates we encountered an error.
     }
   }
 
   // Lookup and invoke the top level main function.
   Dart_Handle script_url = Dart_NewString(canonical_script_name);
-  Dart_Result result = Dart_LookupLibrary(script_url);
-  if (!Dart_IsValidResult(result)) {
-    fprintf(stderr, "%s\n", Dart_GetErrorCString(result));
+  Dart_Handle library = Dart_LookupLibrary(script_url);
+  if (!Dart_IsValid(library)) {
+    fprintf(stderr, "%s\n", Dart_GetError(library));
     Dart_ExitScope();
     Dart_ShutdownIsolate();
     free(canonical_script_name);
     return 255;  // Indicates we encountered an error.
   }
-  Dart_Handle library = Dart_GetResult(result);
-  result = Dart_InvokeStatic(library,
-                             Dart_NewString(""),
-                             Dart_NewString("main"),
-                             0,
-                             NULL);
-
-  if (Dart_IsValidResult(result)) {
-    Dart_Handle result_obj = Dart_GetResult(result);
-    if (Dart_ExceptionOccurred(result_obj)) {
+  Dart_Handle result = Dart_InvokeStatic(library,
+                                         Dart_NewString(""),
+                                         Dart_NewString("main"),
+                                         0,
+                                         NULL);
+  if (Dart_IsValid(result)) {
+    if (Dart_ExceptionOccurred(result)) {
       // Print the exception object.
       fprintf(stderr, "An unhandled exception has been thrown\n");
-      Dart_Result exception_result = Dart_GetException(result_obj);
-      ASSERT(Dart_IsValidResult(exception_result));
-      PrintObject(stderr, Dart_GetResult(exception_result));
+      Dart_Handle exception_result = Dart_GetException(result);
+      ASSERT(Dart_IsValid(exception_result));
+      PrintObject(stderr, exception_result);
       // Print the stack trace.
-      Dart_Result stacktrace = Dart_GetStacktrace(result_obj);
-      ASSERT(Dart_IsValidResult(stacktrace));
-      PrintObject(stderr, Dart_GetResult(stacktrace));
+      Dart_Handle stacktrace = Dart_GetStacktrace(result);
+      ASSERT(Dart_IsValid(stacktrace));
+      PrintObject(stderr, stacktrace);
       fprintf(stderr, "\n");
       Dart_ExitScope();
       Dart_ShutdownIsolate();
       free(canonical_script_name);
       return 255;  // We had an unhandled exception, hence indicate an error.
     }
   } else {
-    fprintf(stderr, "%s\n", Dart_GetErrorCString(result));
+    fprintf(stderr, "%s\n", Dart_GetError(result));
     Dart_ExitScope();
     Dart_ShutdownIsolate();
     free(canonical_script_name);
     return 255;  // Indicates we encountered an error.
   }
   // Keep handling messages until the last active receive port is closed.
   result = Dart_RunLoop();
-  if (!Dart_IsValidResult(result)) {
-    fprintf(stderr, "%s\n", Dart_GetErrorCString(result));
+  if (!Dart_IsValid(result)) {
+    fprintf(stderr, "%s\n", Dart_GetError(result));
     Dart_ExitScope();
     Dart_ShutdownIsolate();
     free(canonical_script_name);
     return 255;  // Indicates we encountered an error.
   }
   free(canonical_script_name);
   Dart_ExitScope();
   // Dump symbol information for the profiler.
   DumpPprofSymbolInfo();
   // Shutdown the isolate.
   Dart_ShutdownIsolate();
   return 0;
 }