Changeset 30739 in vbox for trunk/include/VBox/com/MultiResult.h

Timestamp:

Jul 8, 2010 12:27:42 PM (15 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

63508

Message:

Main: remove VirtualBoxSupportTranslation template, add translation support to generic base class, clean up COM headers more, remove SupportErrorInfo.cpp|h

File:

• trunk/include/VBox/com/MultiResult.h (moved) (moved from trunk/include/VBox/com/SupportErrorInfo.h ) (2 diffs)

trunk/include/VBox/com/MultiResult.h

@@ -33 +33 @@
 #include "VBox/com/string.h"
 
-#include <iprt/cdefs.h>
-
 #include <stdarg.h>
 
-#if !defined (VBOX_WITH_XPCOM)
-interface IVirtualBoxErrorInfo;
-#else
-class IVirtualBoxErrorInfo;
-#endif
-
 namespace com
 {
+
+/**
+ * "First worst" result type.
+ *
+ * Variables of this class are used instead of HRESULT variables when it is
+ * desirable to memorize the "first worst" result code instead of the last
+ * assigned one. In other words, an assignment operation to a variable of this
+ * class will succeed only if the result code to assign has worse severity. The
+ * following table demonstrate this (the first column lists the previous result
+ * code stored in the variable, the first row lists the new result code being
+ * assigned, 'A' means the assignment will take place, '> S_OK' means a warning
+ * result code):
+ *
+ * {{{
+ *             FAILED    > S_OK    S_OK
+ * FAILED        -         -         -
+ * > S_OK        A         -         -
+ * S_OK          A         A         -
+ *
+ * }}}
+ *
+ * In practice, you will need to use a FWResult variable when you call some COM
+ * method B after another COM method A fails and want to return the result code
+ * of A even if B also fails, but want to return the failed result code of B if
+ * A issues a warning or succeeds.
+ */
+class FWResult
+{
+
+public:
+
+    /**
+     * Constructs a new variable. Note that by default this constructor sets the
+     * result code to E_FAIL to make sure a failure is returned to the caller if
+     * the variable is never assigned another value (which is considered as the
+     * improper use of this class).
+     */
+    FWResult (HRESULT aRC = E_FAIL) : mRC (aRC) {}
+
+    FWResult &operator= (HRESULT aRC)
+    {
+        if ((FAILED (aRC) && !FAILED (mRC)) ||
+            (mRC == S_OK && aRC != S_OK))
+            mRC = aRC;
+
+        return *this;
+    }
+
+    operator HRESULT() const { return mRC; }
+
+    HRESULT *operator&() { return &mRC; }
+
+private:
+
+    HRESULT mRC;
+};
 
 /**
@@ -164 +212 @@
 private:
 
-    DECLARE_CLS_NEW_DELETE_NOOP (MultiResult)
+    DECLARE_CLS_NEW_DELETE_NOOP(MultiResult)
 
     static void incCounter();