From 7f783fac8f6c54217e2f4eb42fcf2f8b0236b167 Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Tue, 21 Oct 2014 01:47:11 +0100
Subject: [PATCH] refs #338 CLogHandler: cleaned up the logic for selectively
 enabling console output, with the help of the partial ordering feature of
 CLogPattern::isProperSubsetOf.

---
 src/blackmisc/loghandler.cpp | 15 ++-------------
 src/blackmisc/loghandler.h   | 31 +++++++++++++++++++++++++++----
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/src/blackmisc/loghandler.cpp b/src/blackmisc/loghandler.cpp
index a1a4c6f0b..23c09fdb6 100644
--- a/src/blackmisc/loghandler.cpp
+++ b/src/blackmisc/loghandler.cpp
@@ -54,7 +54,7 @@ namespace BlackMisc
         auto it = std::find_if(m_patternHandlers.begin(), m_patternHandlers.end(), finder);
         if (it == m_patternHandlers.end())
         {
-            auto *handler = new CLogPatternHandler(this, m_enableFallThrough);
+            auto *handler = new CLogPatternHandler(this);
             topologicallySortedInsert(m_patternHandlers, PatternPair(pattern, handler), comparator);
             return handler;
         }
@@ -77,22 +77,11 @@ namespace BlackMisc
         return m_handlers;
     }
 
-    void CLogHandler::enableConsoleOutput(bool enable)
-    {
-        Q_ASSERT(thread() == QThread::currentThread());
-
-        m_enableFallThrough = enable;
-        for (const auto &pair : m_patternHandlers)
-        {
-            pair.second->enableConsoleOutput(enable);
-        }
-    }
-
     bool CLogHandler::isFallThroughEnabled(const QList<CLogPatternHandler *> &handlers) const
     {
         for (const auto *handler : handlers)
         {
-            if (handler->m_enableFallThrough != m_enableFallThrough)
+            if (! handler->m_inheritFallThrough)
             {
                 return handler->m_enableFallThrough;
             }
diff --git a/src/blackmisc/loghandler.h b/src/blackmisc/loghandler.h
index 9dea7dc7a..5e586fcfc 100644
--- a/src/blackmisc/loghandler.h
+++ b/src/blackmisc/loghandler.h
@@ -61,7 +61,11 @@ namespace BlackMisc
         void logRemoteMessage(const BlackMisc::CStatusMessage &message);
 
         //! Enable or disable the default Qt handler.
-        void enableConsoleOutput(bool enable);
+        void enableConsoleOutput(bool enable)
+        {
+            Q_ASSERT(thread() == QThread::currentThread());
+            m_enableFallThrough = enable;
+        }
 
     private:
         void logMessage(const BlackMisc::CStatusMessage &message);
@@ -90,7 +94,25 @@ namespace BlackMisc
          * CLogPatternHandler or the base CLogHandler, if this handler's pattern is a subset of the
          * other handler's pattern. Which is to say, more specific patterns can override less specific patterns.
          */
-        void enableConsoleOutput(bool enable) { Q_ASSERT(thread() == QThread::currentThread()); m_enableFallThrough = enable; }
+        void enableConsoleOutput(bool enable)
+        {
+            Q_ASSERT(thread() == QThread::currentThread());
+            m_inheritFallThrough = false;
+            m_enableFallThrough = enable;
+        }
+
+        /*!
+         * The policy of whether to enable or disable the default Qt handler for messages which match
+         * the relevant pattern will be inherited from the base CLogHandler, or from another CLogPatternHandler
+         * which matches a superset of the messages which this one matches.
+         *
+         * This is the default, but can be used to reverse the effect of calling enableConsoleOutput.
+         */
+        void inheritConsoleOutput()
+        {
+            Q_ASSERT(thread() == QThread::currentThread());
+            m_inheritFallThrough = true;
+        }
 
     signals:
         /*!
@@ -108,8 +130,9 @@ namespace BlackMisc
 
     private:
         friend class CLogHandler;
-        CLogPatternHandler(QObject *parent, bool enableFallThrough) : QObject(parent), m_enableFallThrough(enableFallThrough) {}
-        bool m_enableFallThrough;
+        CLogPatternHandler(QObject *parent) : QObject(parent) {}
+        bool m_inheritFallThrough = true;
+        bool m_enableFallThrough = true;
 
         bool canBeDeleted()
         {