diff --git a/src/mvvmcore/message.cpp b/src/mvvmcore/message.cpp
index 055a257..e39f0a3 100644
--- a/src/mvvmcore/message.cpp
+++ b/src/mvvmcore/message.cpp
@@ -267,7 +267,7 @@ MessageResult *QtMvvm::information(const QString &title, const QString &text, co
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::information(const QString &title, const QString &text, QObject *scope, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::information(const QString &title, const QString &text, QObject *scope, const std::function<void ()> &onResult, const QString &okText)
 {
 	auto result = information(title, text, okText);
 	if(result) {
@@ -277,7 +277,7 @@ void QtMvvm::information(const QString &title, const QString &text, QObject *sco
 	}
 }
 
-void QtMvvm::information(const QString &title, const QString &text, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::information(const QString &title, const QString &text, const std::function<void ()> &onResult, const QString &okText)
 {
 	information(title, text, CoreApp::instance(), onResult, okText);
 }
@@ -294,7 +294,7 @@ MessageResult *QtMvvm::question(const QString &title, const QString &text, const
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::question(const QString &title, const QString &text, QObject *scope, std::function<void (bool)> onResult, const QString &yesText, const QString &noText)
+void QtMvvm::question(const QString &title, const QString &text, QObject *scope, const std::function<void (bool)> &onResult, const QString &yesText, const QString &noText)
 {
 	auto result = question(title, text, yesText, noText);
 	if(result) {
@@ -305,7 +305,7 @@ void QtMvvm::question(const QString &title, const QString &text, QObject *scope,
 	}
 }
 
-void QtMvvm::question(const QString &title, const QString &text, std::function<void (bool)> onResult, const QString &yesText, const QString &noText)
+void QtMvvm::question(const QString &title, const QString &text, const std::function<void (bool)> &onResult, const QString &yesText, const QString &noText)
 {
 	question(title, text, CoreApp::instance(), onResult, yesText, noText);
 }
@@ -320,7 +320,7 @@ MessageResult *QtMvvm::warning(const QString &title, const QString &text, const
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::warning(const QString &title, const QString &text, QObject *scope, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::warning(const QString &title, const QString &text, QObject *scope, const std::function<void ()> &onResult, const QString &okText)
 {
 	auto result = warning(title, text, okText);
 	if(result) {
@@ -330,7 +330,7 @@ void QtMvvm::warning(const QString &title, const QString &text, QObject *scope,
 	}
 }
 
-void QtMvvm::warning(const QString &title, const QString &text, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::warning(const QString &title, const QString &text, const std::function<void ()> &onResult, const QString &okText)
 {
 	warning(title, text, CoreApp::instance(), onResult, okText);
 }
@@ -345,7 +345,7 @@ MessageResult *QtMvvm::critical(const QString &title, const QString &text, const
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::critical(const QString &title, const QString &text, QObject *scope, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::critical(const QString &title, const QString &text, QObject *scope, const std::function<void ()> &onResult, const QString &okText)
 {
 	auto result = critical(title, text, okText);
 	if(result) {
@@ -355,7 +355,7 @@ void QtMvvm::critical(const QString &title, const QString &text, QObject *scope,
 	}
 }
 
-void QtMvvm::critical(const QString &title, const QString &text, std::function<void ()> onResult, const QString &okText)
+void QtMvvm::critical(const QString &title, const QString &text, const std::function<void ()> &onResult, const QString &okText)
 {
 	critical(title, text, CoreApp::instance(), onResult, okText);
 }
@@ -444,7 +444,7 @@ MessageResult *QtMvvm::getInput(const QString &title, const QString &text, const
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::getInput(const QString &title, const QString &text, const char *inputType, QObject *scope, std::function<void (QVariant)> onResult, const QVariant &defaultValue, const QVariantMap &viewProperties, const QString &okText, const QString &cancelText)
+void QtMvvm::getInput(const QString &title, const QString &text, const char *inputType, QObject *scope, const std::function<void (QVariant)> &onResult, const QVariant &defaultValue, const QVariantMap &viewProperties, const QString &okText, const QString &cancelText)
 {
 	auto result = getInput(title, text, inputType, defaultValue, viewProperties, okText, cancelText);
 	if(result) {
@@ -455,7 +455,7 @@ void QtMvvm::getInput(const QString &title, const QString &text, const char *inp
 	}
 }
 
-void QtMvvm::getInput(const QString &title, const QString &text, const char *inputType, std::function<void (QVariant)> onResult, const QVariant &defaultValue, const QVariantMap &viewProperties, const QString &okText, const QString &cancelText)
+void QtMvvm::getInput(const QString &title, const QString &text, const char *inputType, const std::function<void (QVariant)> &onResult, const QVariant &defaultValue, const QVariantMap &viewProperties, const QString &okText, const QString &cancelText)
 {
 	getInput(title, text, inputType, CoreApp::instance(), onResult, defaultValue, viewProperties, okText, cancelText);
 }
@@ -468,7 +468,7 @@ MessageResult *QtMvvm::getExistingDirectory(const QString &title, const QUrl &di
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::getExistingDirectory(QObject *scope, std::function<void (QUrl)> onResult, const QString &title, const QUrl &dir)
+void QtMvvm::getExistingDirectory(QObject *scope, const std::function<void (QUrl)> &onResult, const QString &title, const QUrl &dir)
 {
 	auto result = getExistingDirectory(title, dir);
 	if(result) {
@@ -479,7 +479,7 @@ void QtMvvm::getExistingDirectory(QObject *scope, std::function<void (QUrl)> onR
 	}
 }
 
-void QtMvvm::getExistingDirectory(std::function<void (QUrl)> onResult, const QString &title, const QUrl &dir)
+void QtMvvm::getExistingDirectory(const std::function<void (QUrl)> &onResult, const QString &title, const QUrl &dir)
 {
 	getExistingDirectory(CoreApp::instance(), onResult, title, dir);
 }
@@ -493,7 +493,7 @@ MessageResult *QtMvvm::getOpenFile(const QString &title, const QStringList &supp
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::getOpenFile(QObject *scope, std::function<void (QUrl)> onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
+void QtMvvm::getOpenFile(QObject *scope, const std::function<void (QUrl)> &onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
 {
 	auto result = getOpenFile(title, supportedMimeTypes, dir);
 	if(result) {
@@ -504,7 +504,7 @@ void QtMvvm::getOpenFile(QObject *scope, std::function<void (QUrl)> onResult, co
 	}
 }
 
-void QtMvvm::getOpenFile(std::function<void (QUrl)> onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
+void QtMvvm::getOpenFile(const std::function<void (QUrl)> &onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
 {
 	getOpenFile(CoreApp::instance(), onResult, title, supportedMimeTypes, dir);
 }
@@ -543,7 +543,7 @@ MessageResult *QtMvvm::getSaveFile(const QString &title, const QStringList &supp
 	return CoreApp::showDialog(config);
 }
 
-void QtMvvm::getSaveFile(QObject *scope, std::function<void (QUrl)> onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
+void QtMvvm::getSaveFile(QObject *scope, const std::function<void (QUrl)> &onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
 {
 	auto result = getSaveFile(title, supportedMimeTypes, dir);
 	if(result) {
@@ -554,7 +554,7 @@ void QtMvvm::getSaveFile(QObject *scope, std::function<void (QUrl)> onResult, co
 	}
 }
 
-void QtMvvm::getSaveFile(std::function<void (QUrl)> onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
+void QtMvvm::getSaveFile(const std::function<void (QUrl)> &onResult, const QString &title, const QStringList &supportedMimeTypes, const QUrl &dir)
 {
 	getSaveFile(CoreApp::instance(), onResult, title, supportedMimeTypes, dir);
 }
diff --git a/src/mvvmcore/message.h b/src/mvvmcore/message.h
index 3fd3351..b9fb6d2 100644
--- a/src/mvvmcore/message.h
+++ b/src/mvvmcore/message.h
@@ -151,11 +151,11 @@ Q_MVVMCORE_EXPORT MessageResult *information(const QString &title,
 Q_MVVMCORE_EXPORT void information(const QString &title,
 								   const QString &text,
 								   QObject *scope,
-								   std::function<void()> onResult,
+								   const std::function<void()> &onResult,
 								   const QString &okText = {});
 Q_MVVMCORE_EXPORT void information(const QString &title,
 								   const QString &text,
-								   std::function<void()> onResult,
+								   const std::function<void()> &onResult,
 								   const QString &okText = {});
 
 Q_MVVMCORE_EXPORT MessageResult *question(const QString &title,
@@ -165,12 +165,12 @@ Q_MVVMCORE_EXPORT MessageResult *question(const QString &title,
 Q_MVVMCORE_EXPORT void question(const QString &title,
 								const QString &text,
 								QObject *scope,
-								std::function<void(bool)> onResult,
+								const std::function<void(bool)> &onResult,
 								const QString &yesText = {},
 								const QString &noText = {});
 Q_MVVMCORE_EXPORT void question(const QString &title,
 								const QString &text,
-								std::function<void(bool)> onResult,
+								const std::function<void(bool)> &onResult,
 								const QString &yesText = {},
 								const QString &noText = {});
 
@@ -180,11 +180,11 @@ Q_MVVMCORE_EXPORT MessageResult *warning(const QString &title,
 Q_MVVMCORE_EXPORT void warning(const QString &title,
 							   const QString &text,
 							   QObject *scope,
-							   std::function<void()> onResult,
+							   const std::function<void()> &onResult,
 							   const QString &okText = {});
 Q_MVVMCORE_EXPORT void warning(const QString &title,
 							   const QString &text,
-							   std::function<void()> onResult,
+							   const std::function<void()> &onResult,
 							   const QString &okText = {});
 
 Q_MVVMCORE_EXPORT MessageResult *critical(const QString &title,
@@ -193,11 +193,11 @@ Q_MVVMCORE_EXPORT MessageResult *critical(const QString &title,
 Q_MVVMCORE_EXPORT void critical(const QString &title,
 								const QString &text,
 								QObject *scope,
-								std::function<void()> onResult,
+								const std::function<void()> &onResult,
 								const QString &okText = {});
 Q_MVVMCORE_EXPORT void critical(const QString &title,
 								const QString &text,
-								std::function<void()> onResult,
+								const std::function<void()> &onResult,
 								const QString &okText = {});
 
 Q_MVVMCORE_EXPORT MessageResult *about(const QString &description,
@@ -220,7 +220,7 @@ Q_MVVMCORE_EXPORT void getInput(const QString &title,
 								const QString &text,
 								const char *inputType,
 								QObject *scope,
-								std::function<void(QVariant)> onResult,
+								const std::function<void(QVariant)> &onResult,
 								const QVariant &defaultValue = {},
 								const QVariantMap &viewProperties = {},
 								const QString &okText = {},
@@ -228,7 +228,7 @@ Q_MVVMCORE_EXPORT void getInput(const QString &title,
 Q_MVVMCORE_EXPORT void getInput(const QString &title,
 								const QString &text,
 								const char *inputType,
-								std::function<void(QVariant)> onResult,
+								const std::function<void(QVariant)> &onResult,
 								const QVariant &defaultValue = {},
 								const QVariantMap &viewProperties = {},
 								const QString &okText = {},
@@ -247,7 +247,7 @@ template <typename TEdit>
 inline void getInput(const QString &title,
 					 const QString &text,
 					 QObject *scope,
-					 std::function<void(TEdit)> onResult,
+					 const std::function<void(TEdit)> &onResult,
 					 const QVariant &defaultValue = {},
 					 const QVariantMap &viewProperties = {},
 					 const QString &okText = {},
@@ -259,7 +259,7 @@ inline void getInput(const QString &title,
 template <typename TEdit>
 inline void getInput(const QString &title,
 					 const QString &text,
-					 std::function<void(TEdit)> onResult,
+					 const std::function<void(TEdit)> &onResult,
 					 const QVariant &defaultValue = {},
 					 const QVariantMap &viewProperties = {},
 					 const QString &okText = {},
@@ -272,10 +272,10 @@ inline void getInput(const QString &title,
 Q_MVVMCORE_EXPORT MessageResult *getExistingDirectory(const QString &title = {},
 													  const QUrl &dir = {});
 Q_MVVMCORE_EXPORT void getExistingDirectory(QObject *scope,
-											std::function<void(QUrl)> onResult,
+											const std::function<void(QUrl)> &onResult,
 											const QString &title = {},
 											const QUrl &dir = {});
-Q_MVVMCORE_EXPORT void getExistingDirectory(std::function<void(QUrl)> onResult,
+Q_MVVMCORE_EXPORT void getExistingDirectory(const std::function<void(QUrl)> &onResult,
 											const QString &title = {},
 											const QUrl &dir = {});
 
@@ -283,11 +283,11 @@ Q_MVVMCORE_EXPORT MessageResult *getOpenFile(const QString &title = {},
 											 const QStringList &supportedMimeTypes = {},
 											 const QUrl &dir = {});
 Q_MVVMCORE_EXPORT void getOpenFile(QObject *scope,
-								   std::function<void(QUrl)> onResult,
+								   const std::function<void(QUrl)> &onResult,
 								   const QString &title = {},
 								   const QStringList &supportedMimeTypes = {},
 								   const QUrl &dir = {});
-Q_MVVMCORE_EXPORT void getOpenFile(std::function<void(QUrl)> onResult,
+Q_MVVMCORE_EXPORT void getOpenFile(const std::function<void(QUrl)> &onResult,
 								   const QString &title = {},
 								   const QStringList &supportedMimeTypes = {},
 								   const QUrl &dir = {});
@@ -309,11 +309,11 @@ Q_MVVMCORE_EXPORT MessageResult *getSaveFile(const QString &title = {},
 											 const QStringList &supportedMimeTypes = {},
 											 const QUrl &dir = {});
 Q_MVVMCORE_EXPORT void getSaveFile(QObject *scope,
-								   std::function<void(QUrl)> onResult,
+								   const std::function<void(QUrl)> &onResult,
 								   const QString &title = {},
 								   const QStringList &supportedMimeTypes = {},
 								   const QUrl &dir = {});
-Q_MVVMCORE_EXPORT void getSaveFile(std::function<void(QUrl)> onResult,
+Q_MVVMCORE_EXPORT void getSaveFile(const std::function<void(QUrl)> &onResult,
 								   const QString &title = {},
 								   const QStringList &supportedMimeTypes = {},
 								   const QUrl &dir = {});
diff --git a/src/mvvmcore/message_p.h b/src/mvvmcore/message_p.h
index 5dc1c56..8de7ca4 100644
--- a/src/mvvmcore/message_p.h
+++ b/src/mvvmcore/message_p.h
@@ -1,6 +1,10 @@
 #ifndef QTMVVM_MESSAGE_P_H
 #define QTMVVM_MESSAGE_P_H
 
+#include <QtCore/QHash>
+#include <QtCore/QPointer>
+#include <QtCore/QMetaMethod>
+
 #include "qtmvvmcore_global.h"
 #include "message.h"