Make kconfig_compiler signals actually useful + add unit test

Previously the classes generated by kconfig_compiler would only emit
the defined signals when using the setters provided by that class.
However, when using e.g. KConfigDialog which uses
KConfigSkeletonItem::setProperty() to change the items no signal was
generated.
This patch fixes this by using a wrapper KConfigSkeletonItem
subclass that calls a private itemChanged() method in the generated
class which updates the set of changed properties. As soon as the item
is saved (usrWriteConfig() in the generated class is called) the signal
will be emitted

REVIEW: 115635
REVIEW: 115634

12 files changed, 489 insertions, 32 deletions

diff --git a/autotests/kconfig_compiler/CMakeLists.txt b/autotests/kconfig_compiler/CMakeLists.txt
index a2ebb945..289e9583 100644
--- a/autotests/kconfig_compiler/CMakeLists.txt
+++ b/autotests/kconfig_compiler/CMakeLists.txt
@@ -3,14 +3,19 @@
 #	../kconfig_compiler_kf5 $(srcdir)/test5.kcfg $(srcdir)/test5.kcfgc
 
 macro(GEN_KCFG_TEST_SOURCE _testName _srcs)
+   cmake_parse_arguments(ARG "" "KCFG" "" ${ARGN} )
+   set(_kcfgFile ${ARG_KCFG})
+   if (NOT _kcfgFile)
+      set(_kcfgFile "${_testName}.kcfg")
+   endif()
    add_custom_command(
       OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${_testName}.cpp ${CMAKE_CURRENT_BINARY_DIR}/${_testName}.h
-      COMMAND ${KConfig_KCFGC_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfg ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfgc
-      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfg ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfgc kconfig_compiler_kf5)
+      COMMAND ${KConfig_KCFGC_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/${_kcfgFile} ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfgc
+      DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/${_kcfgFile} ${CMAKE_CURRENT_SOURCE_DIR}/${_testName}.kcfgc kconfig_compiler_kf5)
 
-#   set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${_testName}.h PROPERTIES GENERATED TRUE)
+   # set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${_testName}.h PROPERTIES GENERATED TRUE)
    qt5_generate_moc(${CMAKE_CURRENT_BINARY_DIR}/${_testName}.h ${CMAKE_CURRENT_BINARY_DIR}/${_testName}.moc )
-# do not run automoc on the generated file
+   # do not run automoc on the generated file
    set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/${_testName}.cpp PROPERTIES SKIP_AUTOMOC TRUE)
    set( ${_srcs} ${${_srcs}} ${CMAKE_CURRENT_BINARY_DIR}/${_testName}.cpp ${CMAKE_CURRENT_BINARY_DIR}/${_testName}.h )
 
@@ -197,6 +202,18 @@ target_link_libraries(test_signal KF5::ConfigGui)
 
 ########### next target ###############
 
+set(kconfigcompiler_test_signals_SRCS kconfigcompiler_test_signals.cpp)
+gen_kcfg_test_source(signals_test_singleton kconfigcompiler_test_signals_SRCS KCFG signals_test.kcfg)
+gen_kcfg_test_source(signals_test_no_singleton kconfigcompiler_test_signals_SRCS KCFG signals_test.kcfg)
+gen_kcfg_test_source(signals_test_singleton_dpointer kconfigcompiler_test_signals_SRCS KCFG signals_test.kcfg)
+gen_kcfg_test_source(signals_test_no_singleton_dpointer kconfigcompiler_test_signals_SRCS KCFG signals_test.kcfg)
+add_executable(kconfigcompiler_test_signals ${kconfigcompiler_test_signals_SRCS})
+ecm_mark_as_test(kconfigcompiler_test_signals)
+target_link_libraries(kconfigcompiler_test_signals Qt5::Test KF5::ConfigGui)
+add_test(kconfig-kconfigcompiler-signals kconfigcompiler_test_signals)
+
+########### next target ###############
+
 set(kconfigcompiler_test_SRCS kconfigcompiler_test.cpp )
 add_executable(kconfigcompiler_test ${kconfigcompiler_test_SRCS})
 ecm_mark_as_test(kconfigcompiler_test)
diff --git a/autotests/kconfig_compiler/kconfigcompiler_test_signals.cpp b/autotests/kconfig_compiler/kconfigcompiler_test_signals.cpp
new file mode 100644
index 00000000..3017fe2f
--- /dev/null
+++ b/autotests/kconfig_compiler/kconfigcompiler_test_signals.cpp
@@ -0,0 +1,214 @@
+/*
+Copyright (c) 2014 Alexander Richardson <alex.richardson@gmx.de>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include "signals_test_singleton.h"
+#include "signals_test_no_singleton.h"
+#include "signals_test_singleton_dpointer.h"
+#include "signals_test_no_singleton_dpointer.h"
+#include <QtTest/QtTestGui>
+#include <QtTest/QSignalSpy>
+#include <QtCore/QSharedPointer>
+#include <QtCore/QtGlobal>
+#include <QtCore/QDebug>
+#include <QTemporaryFile>
+#include <QFileInfo>
+#include <functional>
+
+class KConfigCompiler_Test_Signals : public QObject
+{
+    Q_OBJECT
+private Q_SLOTS:
+    void testSetters();
+    void testSetters_data();
+    void testSetProperty();
+    void testSetProperty_data();
+    void initTestCase();
+    void cleanupTestCase();
+};
+
+static SignalsTestNoSingleton* noSingleton;
+static SignalsTestNoSingletonDpointer* noSingletonDpointer;
+
+void KConfigCompiler_Test_Signals::initTestCase()
+{
+    // These tests do a lot quite a few I/O operations, speed that up by using a QTemporaryFile.
+    // At least on Linux this is often a tmpfs which means only RAM operations
+    QTemporaryFile* tempFile1 = new QTemporaryFile(this);
+    QTemporaryFile* tempFile2 = new QTemporaryFile(this);
+    QTemporaryFile* tempFile3 = new QTemporaryFile(this);
+    QTemporaryFile* tempFile4 = new QTemporaryFile(this);
+    QVERIFY(tempFile1->open());
+    QVERIFY(tempFile2->open());
+    QVERIFY(tempFile3->open());
+    QVERIFY(tempFile4->open());
+
+    SignalsTestSingleton::instance(QFileInfo(*tempFile1).absoluteFilePath());
+    SignalsTestSingletonDpointer::instance(QFileInfo(*tempFile2).absoluteFilePath());
+    noSingleton = new SignalsTestNoSingleton(
+                KSharedConfig::openConfig(QFileInfo(*tempFile3).absoluteFilePath(), KConfig::SimpleConfig));
+    noSingletonDpointer = new SignalsTestNoSingletonDpointer(
+                KSharedConfig::openConfig(QFileInfo(*tempFile4).absoluteFilePath(), KConfig::SimpleConfig));
+}
+
+void KConfigCompiler_Test_Signals::cleanupTestCase()
+{
+    //ensure these instances are deleted before the temporary files are closed
+    delete noSingleton;
+    delete noSingletonDpointer;
+    delete SignalsTestSingleton::self();
+    delete SignalsTestSingletonDpointer::self();
+}
+
+struct TestSettersArg {
+    // default constructor required for Q_DECLARE_METATYPE
+    TestSettersArg() : obj(nullptr) {}
+    template<typename T>
+    TestSettersArg(T* object) : obj(object) {
+        // we can also call static methods using object->foo() so this works for all four cases
+        getter = [object]() { return object->foo(); };
+        defaultGetter = [object]() { return object->defaultFooValue(); };
+        setter = [object](const QString& s) { object->setFoo(s); };
+    }
+    KCoreConfigSkeleton* obj;
+    std::function<QString()> getter;
+    std::function<QString()> defaultGetter;
+    std::function<void(const QString&)> setter;
+};
+
+Q_DECLARE_METATYPE(TestSettersArg); // so that QFETCH works
+
+void KConfigCompiler_Test_Signals::testSetters_data()
+{
+    QTest::addColumn<TestSettersArg>("params");
+    QTest::newRow("singleton") << TestSettersArg(SignalsTestSingleton::self());
+    QTest::newRow("singleton dpointer") << TestSettersArg(SignalsTestSingletonDpointer::self());
+    QTest::newRow("non-singleton") << TestSettersArg(noSingleton);
+    QTest::newRow("non-singleton dpointer") << TestSettersArg(noSingleton);
+}
+
+/** Ensure that a signal is emitted whenever the data is changed by using the generated setters */
+void KConfigCompiler_Test_Signals::testSetters()
+{
+    QFETCH(TestSettersArg, params);
+    const char* signal = SIGNAL(fooChanged(QString));
+    const QString defaultValue = QStringLiteral("default");
+    const QString changedValue = QStringLiteral("changed");
+
+    // make sure we are in the default state
+    params.obj->setDefaults();
+    params.obj->writeConfig();
+
+    QList<QVariant> args;
+    QSignalSpy spy(params.obj, signal);
+    QVERIFY2(spy.isValid(), signal);
+
+    //change value via setter, should get signal
+    QCOMPARE(params.getter(), defaultValue);
+    QCOMPARE(defaultValue, params.defaultGetter());
+    QCOMPARE(params.getter(), params.defaultGetter());
+    QVERIFY(changedValue != params.getter());
+    params.setter(changedValue);
+    QCOMPARE(params.getter(), changedValue);
+    QCOMPARE(spy.count(), 0); //should have no change yet, only after writeConfig()
+    params.obj->writeConfig();
+    QCOMPARE(spy.count(), 1);
+    args = spy.takeFirst();
+    QCOMPARE(args.size(), 1);
+    QCOMPARE(args[0].value<QString>(), changedValue);
+
+    //reset to default values via setDefaults()
+    QVERIFY(params.getter() != params.defaultGetter());
+    QVERIFY(params.getter() != defaultValue);
+    QCOMPARE(params.getter(), changedValue);
+    params.obj->setDefaults();
+    QCOMPARE(params.getter(), params.defaultGetter());
+    QCOMPARE(params.getter(), defaultValue);
+
+    QCOMPARE(spy.count(), 0); //should have no change yet, only after writeConfig()
+    params.obj->writeConfig();
+    //TODO: This currently fails since setDefaults() does not yet cause emitting a signal
+    QCOMPARE(spy.count(), 1);
+    args = spy.takeFirst();
+    QCOMPARE(args.size(), 1);
+    QCOMPARE(args[0].value<QString>(), defaultValue);
+}
+
+Q_DECLARE_METATYPE(KCoreConfigSkeleton*);
+
+void KConfigCompiler_Test_Signals::testSetProperty_data()
+{
+    QTest::addColumn<KCoreConfigSkeleton*>("obj");
+    QTest::newRow("singleton") << static_cast<KCoreConfigSkeleton*>(SignalsTestSingleton::self());
+    QTest::newRow("singleton dpointer") << static_cast<KCoreConfigSkeleton*>(SignalsTestSingletonDpointer::self());
+    QTest::newRow("non-singleton") << static_cast<KCoreConfigSkeleton*>(noSingleton);
+    QTest::newRow("non-singleton dpointer") << static_cast<KCoreConfigSkeleton*>(noSingletonDpointer);
+}
+
+/** Test that the signal is emitted when modifying the values using the underlying KConfigSkeletonItem (bypassing the setters) */
+void KConfigCompiler_Test_Signals::testSetProperty()
+{
+    QFETCH(KCoreConfigSkeleton*, obj);
+    const char* signal = SIGNAL(fooChanged(QString));
+    const QString propertyName = QStringLiteral("foo");
+    const QString defaultValue = QStringLiteral("default");
+    const QString newValue = QStringLiteral("changed");
+    obj->setDefaults();
+    obj->writeConfig();
+
+    KConfigSkeletonItem* item = obj->findItem(propertyName);
+    QVERIFY2(item, "Item must exist");
+    QVERIFY2(!item->isImmutable(), "Item must not be immutable");
+    QVERIFY2(!obj->isImmutable(propertyName), "Item must not be immutable");
+
+    //listen for all expected signals
+    QSignalSpy spy(obj, signal);
+    QVERIFY2(spy.isValid(), signal);
+
+    QVERIFY(item->isEqual(defaultValue));
+    QVERIFY(!item->isEqual(newValue));
+
+    item->setProperty(newValue); //change value now
+    //should have no change yet, only after writeConfig()
+    QCOMPARE(spy.count(), 0);
+    obj->writeConfig();
+    //now check for the signal emissions
+    QCOMPARE(spy.count(), 1);
+    QList<QVariant> args = spy.takeFirst();
+    QCOMPARE(args.size(), 1);
+    QVERIFY(item->isEqual(args[0]));
+
+    //now reset to default
+    QVERIFY(!item->isEqual(defaultValue));
+    item->setDefault();
+    QVERIFY(item->isEqual(defaultValue));
+    //should have no change yet, only after writeConfig()
+    QCOMPARE(spy.count(), 0);
+    obj->writeConfig();
+    //now check for the signal emissions
+    QCOMPARE(spy.count(), 1);
+    args = spy.takeFirst();
+    QCOMPARE(args.size(), 1);
+    QVERIFY(item->isEqual(args[0]));
+}
+
+QTEST_MAIN(KConfigCompiler_Test_Signals)
+
+#include "kconfigcompiler_test_signals.moc"
diff --git a/autotests/kconfig_compiler/signals_test.kcfg b/autotests/kconfig_compiler/signals_test.kcfg
new file mode 100644
index 00000000..766c56eb
--- /dev/null
+++ b/autotests/kconfig_compiler/signals_test.kcfg
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Author: Alex Richardson -->
+<kcfg xmlns="http://www.kde.org/standards/kcfg/1.0"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+      xsi:schemaLocation="http://www.kde.org/standards/kcfg/1.0
+      http://www.kde.org/standards/kcfg/1.0/kcfg.xsd" >
+  <kcfgfile arg="true"/>
+  <signal name="fooChanged">
+    <argument type="String">foo</argument>
+  </signal>
+  <group name="Something">
+    <entry key="foo" type="String">
+      <default>default</default>
+      <emit signal="fooChanged" />
+    </entry>
+  </group>
+</kcfg>
diff --git a/autotests/kconfig_compiler/signals_test_no_singleton.kcfgc b/autotests/kconfig_compiler/signals_test_no_singleton.kcfgc
new file mode 100644
index 00000000..4d096e08
--- /dev/null
+++ b/autotests/kconfig_compiler/signals_test_no_singleton.kcfgc
@@ -0,0 +1,9 @@
+File=signals_test.kcfg
+ClassName=SignalsTestNoSingleton
+Singleton=false
+Mutators=true
+MemberVariables=private
+GlobalEnums=false
+UseEnumTypes=false
+ItemAccessors=false
+DefaultValueGetters=true
diff --git a/autotests/kconfig_compiler/signals_test_no_singleton_dpointer.kcfgc b/autotests/kconfig_compiler/signals_test_no_singleton_dpointer.kcfgc
new file mode 100644
index 00000000..11b7c435
--- /dev/null
+++ b/autotests/kconfig_compiler/signals_test_no_singleton_dpointer.kcfgc
@@ -0,0 +1,9 @@
+File=signals_test.kcfg
+ClassName=SignalsTestNoSingletonDpointer
+Singleton=false
+Mutators=true
+MemberVariables=dpointer
+GlobalEnums=false
+UseEnumTypes=false
+ItemAccessors=false
+DefaultValueGetters=true
diff --git a/autotests/kconfig_compiler/signals_test_singleton.kcfgc b/autotests/kconfig_compiler/signals_test_singleton.kcfgc
new file mode 100644
index 00000000..59e04452
--- /dev/null
+++ b/autotests/kconfig_compiler/signals_test_singleton.kcfgc
@@ -0,0 +1,9 @@
+File=signals_test.kcfg
+ClassName=SignalsTestSingleton
+Singleton=true
+Mutators=true
+MemberVariables=private
+GlobalEnums=false
+UseEnumTypes=false
+ItemAccessors=false
+DefaultValueGetters=true
diff --git a/autotests/kconfig_compiler/signals_test_singleton_dpointer.kcfgc b/autotests/kconfig_compiler/signals_test_singleton_dpointer.kcfgc
new file mode 100644
index 00000000..1f13493a
--- /dev/null
+++ b/autotests/kconfig_compiler/signals_test_singleton_dpointer.kcfgc
@@ -0,0 +1,9 @@
+File=signals_test.kcfg
+ClassName=SignalsTestSingletonDpointer
+Singleton=true
+Mutators=true
+MemberVariables=dpointer
+GlobalEnums=false
+UseEnumTypes=false
+ItemAccessors=false
+DefaultValueGetters=true
diff --git a/autotests/kconfig_compiler/test_signal.cpp.ref b/autotests/kconfig_compiler/test_signal.cpp.ref
index fd2d4bc9..35b5cba2 100644
--- a/autotests/kconfig_compiler/test_signal.cpp.ref
+++ b/autotests/kconfig_compiler/test_signal.cpp.ref
@@ -30,19 +30,21 @@ TestSignal::TestSignal(  )
 {
   Q_ASSERT(!s_globalTestSignal()->q);
   s_globalTestSignal()->q = this;
+  KConfigCompilerSignallingItem::NotifyFunction notifyFunction = static_cast<KConfigCompilerSignallingItem::NotifyFunction>(&TestSignal::itemChanged);
+
   setCurrentGroup( QLatin1String( "Appearance" ) );
 
-  KConfigSkeleton::ItemString  *itemEmoticonTheme;
-  itemEmoticonTheme = new KConfigSkeleton::ItemString( currentGroup(), QLatin1String( "emoticonTheme" ), mEmoticonTheme, QLatin1String( "Default" ) );
+  KConfigCompilerSignallingItem  *itemEmoticonTheme;
+  itemEmoticonTheme = new KConfigCompilerSignallingItem(new KConfigSkeleton::ItemString( currentGroup(), QLatin1String( "emoticonTheme" ), mEmoticonTheme, QLatin1String( "Default" ) ), this, notifyFunction, signalEmoticonSettingsChanged);
   addItem( itemEmoticonTheme, QLatin1String( "emoticonTheme" ) );
-  KConfigSkeleton::ItemBool  *itemUseEmoticon;
-  itemUseEmoticon = new KConfigSkeleton::ItemBool( currentGroup(), QLatin1String( "useEmoticon" ), mUseEmoticon, true );
+  KConfigCompilerSignallingItem  *itemUseEmoticon;
+  itemUseEmoticon = new KConfigCompilerSignallingItem(new KConfigSkeleton::ItemBool( currentGroup(), QLatin1String( "useEmoticon" ), mUseEmoticon, true ), this, notifyFunction, signalEmoticonSettingsChanged);
   addItem( itemUseEmoticon, QLatin1String( "useEmoticon" ) );
-  KConfigSkeleton::ItemBool  *itemEmoticonRequireSpace;
-  itemEmoticonRequireSpace = new KConfigSkeleton::ItemBool( currentGroup(), QLatin1String( "emoticonRequireSpace" ), mEmoticonRequireSpace, true );
+  KConfigCompilerSignallingItem  *itemEmoticonRequireSpace;
+  itemEmoticonRequireSpace = new KConfigCompilerSignallingItem(new KConfigSkeleton::ItemBool( currentGroup(), QLatin1String( "emoticonRequireSpace" ), mEmoticonRequireSpace, true ), this, notifyFunction, signalEmoticonSettingsChanged);
   addItem( itemEmoticonRequireSpace, QLatin1String( "emoticonRequireSpace" ) );
-  KConfigSkeleton::ItemString  *itemStylePath;
-  itemStylePath = new KConfigSkeleton::ItemString( currentGroup(), QLatin1String( "stylePath" ), mStylePath );
+  KConfigCompilerSignallingItem  *itemStylePath;
+  itemStylePath = new KConfigCompilerSignallingItem(new KConfigSkeleton::ItemString( currentGroup(), QLatin1String( "stylePath" ), mStylePath ), this, notifyFunction, signalStyleChanged);
   addItem( itemStylePath, QLatin1String( "stylePath" ) );
   KConfigSkeleton::ItemString  *itemStyleCSSVariant;
   itemStyleCSSVariant = new KConfigSkeleton::ItemString( currentGroup(), QLatin1String( "styleVariant" ), mStyleCSSVariant );
@@ -69,5 +71,9 @@ bool TestSignal::usrWriteConfig()
   return true;
 }
 
+void TestSignal::itemChanged(quint64 flags) {
+  mSettingsChanged |= flags;
+}
+
 #include "test_signal.moc"
 
diff --git a/autotests/kconfig_compiler/test_signal.h.ref b/autotests/kconfig_compiler/test_signal.h.ref
index 737718d0..19b8b400 100644
--- a/autotests/kconfig_compiler/test_signal.h.ref
+++ b/autotests/kconfig_compiler/test_signal.h.ref
@@ -132,6 +132,9 @@ class TestSignal : public KConfigSkeleton
     */
     void styleChanged(const QString & stylePath, const QString & StyleCSSVariant);
 
+  private:
+    void itemChanged(quint64 flags);
+
   protected:
     TestSignal();
     friend class TestSignalHelper;
diff --git a/src/core/kcoreconfigskeleton.cpp b/src/core/kcoreconfigskeleton.cpp
index d9b95b4b..98d9cdcc 100644
--- a/src/core/kcoreconfigskeleton.cpp
+++ b/src/core/kcoreconfigskeleton.cpp
@@ -1339,3 +1339,77 @@ KConfigSkeletonItem *KCoreConfigSkeleton::findItem(const QString &name) const
     return d->mItemDict.value(name);
 }
 
+KConfigCompilerSignallingItem::KConfigCompilerSignallingItem(KConfigSkeletonItem* item, QObject* object,
+        KConfigCompilerSignallingItem::NotifyFunction targetFunction, quint64 userData)
+    : KConfigSkeletonItem(item->group(), item->key()), mItem(item), mTargetFunction(targetFunction),
+    mObject(object), mUserData(userData)
+{
+    Q_ASSERT(mTargetFunction);
+    Q_ASSERT(mItem);
+    Q_ASSERT(mObject);
+}
+
+KConfigCompilerSignallingItem::~KConfigCompilerSignallingItem()
+{
+}
+
+bool KConfigCompilerSignallingItem::isEqual(const QVariant& p) const
+{
+    return mItem->isEqual(p);
+}
+
+QVariant KConfigCompilerSignallingItem::property() const
+{
+    return mItem->property();
+}
+
+void KConfigCompilerSignallingItem::readConfig(KConfig* c)
+{
+    QVariant oldValue = mItem->property();
+    mItem->readConfig(c);
+    //readConfig() changes mIsImmutable, update it here as well
+    KConfigGroup cg(c, mGroup );
+    readImmutability(cg);
+    if (!mItem->isEqual(oldValue)) {
+        invokeNotifyFunction();
+    }
+}
+
+void KConfigCompilerSignallingItem::readDefault(KConfig* c)
+{
+    mItem->readDefault(c);
+    //readDefault() changes mIsImmutable, update it here as well
+    KConfigGroup cg(c, mGroup );
+    readImmutability(cg);
+}
+
+void KConfigCompilerSignallingItem::writeConfig(KConfig* c)
+{
+    mItem->writeConfig(c);
+}
+
+void KConfigCompilerSignallingItem::setDefault()
+{
+    QVariant oldValue = mItem->property();
+    mItem->setDefault();
+    if (!mItem->isEqual(oldValue)) {
+        invokeNotifyFunction();
+    }
+}
+
+void KConfigCompilerSignallingItem::setProperty(const QVariant& p)
+{
+    if (!mItem->isEqual(p)) {
+        mItem->setProperty(p);
+        invokeNotifyFunction();
+    }
+}
+
+void KConfigCompilerSignallingItem::swapDefault()
+{
+    QVariant oldValue = mItem->property();
+    mItem->swapDefault();
+    if (!mItem->isEqual(oldValue)) {
+        invokeNotifyFunction();
+    }
+}
diff --git a/src/core/kcoreconfigskeleton.h b/src/core/kcoreconfigskeleton.h
index c1a15877..9cd07994 100644
--- a/src/core/kcoreconfigskeleton.h
+++ b/src/core/kcoreconfigskeleton.h
@@ -304,6 +304,57 @@ protected:
 };
 
 /**
+ * \class KConfigSkeletonChangeNotifyingItem kcoreconfigskeleton.h <KConfigSkeletonChangeNotifyingItem>
+ *
+ * @author Alex Richardson
+ * @see KConfigSkeletonItem
+ *
+ *
+ * This class wraps a @ref KConfigSkeletonItem and invokes a function whenever the value changes.
+ * That function must take one quint64 parameter. Whenever the property value of the wrapped KConfigSkeletonItem
+ * changes this function will be invoked with the stored user data passed in the constructor.
+ * It does not call a function with the new value since this class is designed solely for the kconfig_compiler generated
+ * code and is therefore probably not suited for any other usecases.
+ */
+class KCONFIGCORE_EXPORT KConfigCompilerSignallingItem : public KConfigSkeletonItem
+{
+public:
+    typedef void (QObject::* NotifyFunction)(quint64 arg);
+    /**
+    * Constructor.
+    *
+    * @param item the KConfigSkeletonItem to wrap
+    * @param targetFunction the method to invoke whenever the value of @p item changes
+    * @param object The object on which the method is invoked.
+    * @param userData This data will be passed to @p targetFunction on every property change
+    */
+    KConfigCompilerSignallingItem(KConfigSkeletonItem *item, QObject* object,
+            NotifyFunction targetFunction, quint64 userData);
+    virtual ~KConfigCompilerSignallingItem();
+
+    virtual void readConfig(KConfig *) Q_DECL_OVERRIDE;
+    virtual void writeConfig(KConfig *) Q_DECL_OVERRIDE;
+    virtual void readDefault(KConfig *) Q_DECL_OVERRIDE;
+    virtual void setProperty(const QVariant &p) Q_DECL_OVERRIDE;
+    virtual bool isEqual(const QVariant &p) const Q_DECL_OVERRIDE;
+    virtual QVariant property() const Q_DECL_OVERRIDE;
+    virtual void setDefault() Q_DECL_OVERRIDE;
+    virtual void swapDefault() Q_DECL_OVERRIDE;
+private:
+    inline void invokeNotifyFunction()
+    {
+        // call the pointer to member function using the strange ->* operator
+        (mObject->*mTargetFunction)(mUserData);
+    }
+private:
+    QScopedPointer<KConfigSkeletonItem> mItem;
+    NotifyFunction mTargetFunction;
+    QObject* mObject;
+    quint64 mUserData;
+};
+
+
+/**
  * \class KCoreConfigSkeleton kcoreconfigskeleton.h <KCoreConfigSkeleton>
  *
  * @short Class for handling preferences settings for an application.
diff --git a/src/kconfig_compiler/kconfig_compiler.cpp b/src/kconfig_compiler/kconfig_compiler.cpp
index 0c4254a2..7d84cfbc 100644
--- a/src/kconfig_compiler/kconfig_compiler.cpp
+++ b/src/kconfig_compiler/kconfig_compiler.cpp
@@ -1152,12 +1152,17 @@ static QString itemDeclaration(const CfgEntry *e, const CfgConfig &cfg)
         return QString();
     }
 
+    QString type;
+    if (!e->signalList().isEmpty()) {
+        type = "KConfigCompilerSignallingItem";
+    } else {
+        type = cfg.inherits + "::Item" + itemType(e->type());
+    }
+
     QString fCap = e->name();
     fCap[0] = fCap[0].toUpper();
-    return "  " + cfg.inherits + "::Item" + itemType(e->type()) +
-           "  *item" + fCap +
-           ((!e->param().isEmpty()) ? (QString("[%1]").arg(e->paramMax() + 1)) : QString()) +
-           ";\n";
+    return "  " + type + "  *item" + fCap +
+            ( (!e->param().isEmpty())?(QString("[%1]").arg(e->paramMax()+1)) : QString()) + ";\n";
 }
 
 // returns the name of an item variable
@@ -1192,24 +1197,41 @@ static QString itemPath(const CfgEntry *e, const CfgConfig &cfg)
     return result;
 }
 
-QString newItem(const QString &type, const QString &name, const QString &key,
-                const QString &defaultValue, const CfgConfig &cfg, const QString &param = QString())
-{
-    QString t = "new " + cfg.inherits + "::Item" + itemType(type) +
-                "( currentGroup(), " + key + ", " + varPath(name, cfg) + param;
-    if (type == "Enum") {
-        t += ", values" + name;
+QString newItem(const CfgEntry* entry, const QString &key, const QString& defaultValue,
+                const CfgConfig &cfg, const QString &param = QString()) {
+
+    QList<Signal> sigs = entry->signalList();
+    QString t;
+    if (!sigs.isEmpty()) {
+        t += "new KConfigCompilerSignallingItem(";
+    }
+    t += "new "+ cfg.inherits + "::Item" + itemType(entry->type()) + "( currentGroup(), "
+            + key + ", " + varPath( entry->name(), cfg ) + param;
+
+    if (entry->type() == "Enum") {
+        t += ", values" + entry->name();
     }
     if (!defaultValue.isEmpty()) {
         t += ", ";
-        if (type == "String") {
+        if (entry->type() == "String") {
             t += defaultValue;
         } else {
             t += defaultValue;
         }
     }
-    t += " );";
+    t += " )";
 
+    if (!sigs.isEmpty()) {
+        t += ", this, notifyFunction, ";
+        //append the signal flags
+        for (int i = 0; i < sigs.size(); ++i) {
+            if (i != 0)
+                t += " | ";
+            t += signalEnumName(sigs[i].name);
+        }
+        t += ")";
+    }
+    t += ";";
     return t;
 }
 
@@ -2019,6 +2041,10 @@ int main(int argc, char **argv)
             h << ");" << endl;
         }
         h << endl;
+
+        h << "  private:" << endl;
+        h << "    void itemChanged(quint64 flags);" << endl;
+        h << endl;
     }
 
     h << "  protected:" << endl;
@@ -2185,7 +2211,10 @@ int main(int argc, char **argv)
         }
         cpp << endl << "    // items" << endl;
         for (itEntry = entries.constBegin(); itEntry != entries.constEnd(); ++itEntry) {
-            cpp << "    " + cfg.inherits + "::Item" << itemType((*itEntry)->type()) << " *" << itemVar(*itEntry, cfg);
+            const QString declType = (*itEntry)->signalList().isEmpty()
+                    ? QString(cfg.inherits + "::Item" + itemType((*itEntry)->type()))
+                    : "KConfigCompilerSignallingItem";
+            cpp << "    " << declType << " *" << itemVar( *itEntry, cfg );
             if (!(*itEntry)->param().isEmpty()) {
                 cpp << QString("[%1]").arg((*itEntry)->paramMax() + 1);
             }
@@ -2302,6 +2331,14 @@ int main(int argc, char **argv)
 
     group.clear();
 
+    if (hasSignals) {
+        // this cast to base-class pointer-to-member is valid C++
+        // http://stackoverflow.com/questions/4272909/is-it-safe-to-upcast-a-method-pointer-and-use-it-with-base-class-pointer/
+        cpp << "  KConfigCompilerSignallingItem::NotifyFunction notifyFunction ="
+            << " static_cast<KConfigCompilerSignallingItem::NotifyFunction>(&"
+            << cfg.className << "::itemChanged);" << endl << endl;
+    }
+
     for (itEntry = entries.constBegin(); itEntry != entries.constEnd(); ++itEntry) {
         if ((*itEntry)->group() != group) {
             if (!group.isEmpty()) {
@@ -2353,7 +2390,7 @@ int main(int argc, char **argv)
         if ((*itEntry)->param().isEmpty()) {
             // Normal case
             cpp << "  " << itemPath(*itEntry, cfg) << " = "
-                << newItem((*itEntry)->type(), (*itEntry)->name(), key, (*itEntry)->defaultValue(), cfg) << endl;
+                << newItem((*itEntry), key, (*itEntry)->defaultValue(), cfg) << endl;
 
             if (!(*itEntry)->minValue().isEmpty()) {
                 cpp << "  " << itemPath(*itEntry, cfg) << "->setMinValue(" << (*itEntry)->minValue() << ");" << endl;
@@ -2388,8 +2425,7 @@ int main(int argc, char **argv)
                 }
 
                 cpp << "  " << itemVarStr << " = "
-                    << newItem((*itEntry)->type(), (*itEntry)->name(), paramString(key, *itEntry, i), defaultStr, cfg,  QString("[%1]").arg(i))
-                    << endl;
+                    << newItem((*itEntry), paramString(key, *itEntry, i), defaultStr, cfg, QString("[%1]").arg(i)) << endl;
 
                 if (cfg.setUserTexts) {
                     cpp << userTextsFunctions(*itEntry, cfg, itemVarStr, (*itEntry)->paramName());
@@ -2537,10 +2573,13 @@ int main(int argc, char **argv)
         cpp << "  " << varPath("settingsChanged", cfg) << " = 0;" << endl;
         cpp << "  return true;" << endl;
         cpp << "}" << endl;
-    }
 
-    // Add includemoc if they are signals defined.
-    if (hasSignals) {
+        cpp << endl;
+        cpp << "void " << cfg.className << "::" << "itemChanged(quint64 flags) {" << endl;
+        cpp << "  " << varPath("settingsChanged", cfg) << " |= flags;" << endl;
+        cpp << "}" << endl;
+
+        // Add includemoc if they are signals defined.
         cpp << endl;
         cpp << "#include \"" << mocFileName << "\"" << endl;
         cpp << endl;