--- /dev/null
+/****************************************************************************
+**
+** Copyright (C) Qxt Foundation. Some rights reserved.
+**
+** This file is part of the QxtCore module of the Qt eXTension library
+**
+** This library is free software; you can redistribute it and/or modify it
+** under the terms of th Common Public License, version 1.0, as published by
+** IBM.
+**
+** This file is provided "AS IS", without WARRANTIES OR CONDITIONS OF ANY
+** KIND, EITHER EXPRESS OR IMPLIED INCLUDING, WITHOUT LIMITATION, ANY
+** WARRANTIES OR CONDITIONS OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY OR
+** FITNESS FOR A PARTICULAR PURPOSE.
+**
+** You should have received a copy of the CPL along with this file.
+** See the LICENSE file and the cpl1.0.txt file included with the source
+** distribution for more information. If you did not receive a copy of the
+** license, contact the Qxt Foundation.
+**
+** <http://libqxt.sourceforge.net> <foundation@libqxt.org>
+**
+****************************************************************************/
+
+#ifndef QXTBOUNDFUNCTION_H
+#define QXTBOUNDFUNCTION_H
+
+#include <QObject>
+#include <QMetaObject>
+#include <QGenericArgument>
+#include <qxtmetaobject.h>
+#include <qxtnull.h>
+#include <QThread>
+#include <QtDebug>
+
+/**
+ * \class QxtBoundFunction
+ * \ingroup QxtCore
+ * \brief Binds parameters to a function call
+ *
+ * A bound function is very similar to what the C++ FAQ Lite refers to as "functionoids."
+ * (http://www.parashift.com/c++-faq-lite/pointers-to-members.html#faq-33.10)
+ * It is similar in use to a function pointer, but allows any or all parameters to be
+ * pre-filled with constant values. The remaining parameters are specified when the
+ * function is invoked, for instance, by a Qt signal connection.
+ *
+ * By far, the most common expected use is to provide a parameter to a slot when the
+ * signal doesn't have offer one. Many developers new to Qt try to write code like this:
+ * \code
+ * connect(button, SIGNAL(clicked()), lineEdit, SLOT(setText("Hello, world")));
+ * \endcode
+ * Experienced Qt developers will immediately spot the flaw here. The typical solution
+ * is to create a short, one-line wrapper slot that invokes the desired function. Some
+ * clever developers may even use QSignalMapper to handle slots that only need one
+ * int or QString parameter.
+ *
+ * QxtBoundFunction enables the previous connect statement to be written like this:
+ * \code
+ * connect(button, SIGNAL(clicked()), QxtMetaObject::bind(lineEdit, SLOT(setText(QString)), Q_ARG(QString, "Hello, world!")));
+ * \code
+ * This accomplishes the same result without having to create a new slot, or worse,
+ * an entire object, just to pass a constant value.
+ *
+ * Additionally, through the use of the QXT_BIND macro, parameters from the signal
+ * can be rearranged, skipped, or passed alongside constant arguments provided
+ * with the Q_ARG macro. This can be used to provide stateful callbacks to a
+ * generic function, for example.
+ *
+ * Many kinds of functions can be bound. The most common binding applies to
+ * Qt signals and slots, but standard C/C++ functions can be bound as well.
+ * Future development may add the ability to bind to C++ member functions,
+ * and developers can make custom QxtBoundFunction subclasses for even more
+ * flexibility if necessary.
+ */
+class QxtBoundFunction : public QObject
+{
+ Q_OBJECT
+public:
+ /**
+ * Invokes the bound function and returns a value.
+ *
+ * The template parameter should be the return type of the invoked function. This overload accepts
+ * QVariant parameters and will guess the data type of each parameter based on the type of the QVariant.
+ */
+ template <class T>
+ inline QxtNullable<T> invoke(QXT_PROTO_10ARGS(QVariant))
+ {
+ if (!parent() || QThread::currentThread() == parent()->thread())
+ return invoke<T>(Qt::DirectConnection, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+#if QT_VERSION >= 0x040300
+ return invoke<T>(Qt::BlockingQueuedConnection, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+#else
+ qWarning() << "QxtBoundFunction::invoke: Cannot return a value using a queued connection";
+ return qxtNull;
+#endif
+ }
+
+ /**
+ * Invokes the bound function and returns a value.
+ *
+ * The template parameter should be the return type of the invoked function. This overload accepts
+ * QGenericArgument parameters, expressed using the Q_ARG() macro.
+ */
+ template <class T>
+ QxtNullable<T> invoke(Qt::ConnectionType type, QVariant p1, QXT_PROTO_9ARGS(QVariant))
+ {
+ if (type == Qt::QueuedConnection)
+ {
+ qWarning() << "QxtBoundFunction::invoke: Cannot return a value using a queued connection";
+ return qxtNull;
+ }
+ T retval;
+ // I know this is a totally ugly function call
+ if (invoke(type, QGenericReturnArgument(qVariantFromValue<T>(*reinterpret_cast<T*>(0)).typeName(), reinterpret_cast<void*>(&retval)),
+ p1, p2, p3, p4, p5, p6, p7, p8, p9, p10))
+ {
+ return retval;
+ }
+ else
+ {
+ return qxtNull;
+ }
+ }
+
+ /**
+ * Invokes the bound function, discarding the return value.
+ *
+ * This overload accepts QVariant parameters and will guess the data type of each
+ * parameter based on the type of the QVariant.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ inline bool invoke(QVariant p1, QXT_PROTO_9ARGS(QVariant))
+ {
+ return invoke(Qt::AutoConnection, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+ }
+ /**
+ * Invokes the bound function, discarding the return value.
+ *
+ * This overload accepts QVariant parameters and will guess the data type of each
+ * parameter based on the type of the QVariant. It also allows you to specify the
+ * connection type, allowing the bound function to be invoked across threads using
+ * the Qt event loop.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ bool invoke(Qt::ConnectionType, QVariant p1, QXT_PROTO_9ARGS(QVariant));
+
+ /**
+ * Invokes the bound function, discarding the return value.
+ *
+ * This overload accepts QGenericArgument parameters, expressed using the Q_ARG()
+ * macro.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ inline bool invoke(QXT_PROTO_10ARGS(QGenericArgument))
+ {
+ return invoke(Qt::AutoConnection, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+ }
+ /**
+ * Invokes the bound function, discarding the return value.
+ *
+ * This overload accepts QGenericArgument parameters, expressed using the Q_ARG()
+ * macro. It also allows you to specify the connection type, allowing the bound
+ * function to be invoked across threads using the Qt event loop.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ inline bool invoke(Qt::ConnectionType type, QXT_PROTO_10ARGS(QGenericArgument)) {
+ return invoke(type, QGenericReturnArgument(), p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+ }
+
+ /**
+ * Invokes the bound function and assigns the return value to a parameter passed by reference.
+ *
+ * Use the Q_RETURN_ARG() macro to pass a reference to an assignable object of the function's
+ * return type. When the function completes, its return value will be stored in that object.
+ *
+ * This overload accepts QVariant parameters and will guess the data type of each
+ * parameter based on the type of the QVariant.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ inline bool invoke(QGenericReturnArgument returnValue, QVariant p1, QXT_PROTO_9ARGS(QVariant))
+ {
+ return invoke(Qt::AutoConnection, returnValue, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+ }
+ /**
+ * Invokes the bound function and assigns the return value to a parameter passed by reference.
+ *
+ * Use the Q_RETURN_ARG() macro to pass a reference to an assignable object of the function's
+ * return type. When the function completes, its return value will be stored in that object.
+ *
+ * This overload accepts QVariant parameters and will guess the data type of each
+ * parameter based on the type of the QVariant. It also allows you to specify the
+ * connection type, allowing the bound function to be invoked across threads using
+ * the Qt event loop.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ bool invoke(Qt::ConnectionType type, QGenericReturnArgument returnValue, QVariant p1, QXT_PROTO_9ARGS(QVariant));
+
+ /**
+ * Invokes the bound function and assigns the return value to a parameter passed by reference.
+ *
+ * Use the Q_RETURN_ARG() macro to pass a reference to an assignable object of the function's
+ * return type. When the function completes, its return value will be stored in that object.
+ *
+ * This overload accepts QGenericArgument parameters, expressed using the Q_ARG()
+ * macro.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ inline bool invoke(QGenericReturnArgument returnValue, QXT_PROTO_10ARGS(QGenericArgument))
+ {
+ return invoke(Qt::AutoConnection, returnValue, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10);
+ }
+ /**
+ * Invokes the bound function and assigns the return value to a parameter passed by reference.
+ *
+ * Use the Q_RETURN_ARG() macro to pass a reference to an assignable object of the function's
+ * return type. When the function completes, its return value will be stored in that object.
+ *
+ * This overload accepts QGenericArgument parameters, expressed using the Q_ARG()
+ * macro. It also allows you to specify the connection type, allowing the bound
+ * function to be invoked across threads using the Qt event loop.
+ *
+ * This function returns true if the invocation was successful, otherwise it
+ * returns false.
+ */
+ bool invoke(Qt::ConnectionType type, QGenericReturnArgument returnValue, QXT_PROTO_10ARGS(QGenericArgument));
+
+protected:
+#ifndef QXT_DOXYGEN_RUN
+ QxtBoundFunction(QObject* parent = 0);
+#endif
+
+ /**
+ * Performs the work of invoking the bound function.
+ *
+ * This function is pure virtual. The various QxtMetaObject::bind() functions return opaque subclasses
+ * of QxtBoundFunction. If you wish to create a new kind of bound function, reimplement this function to
+ * perform the invocation and assign the function's return value, if any, to the returnValue parameter.
+ *
+ * This function should return true if the invocation is successful and false if an error occurs.
+ */
+ virtual bool invokeImpl(Qt::ConnectionType type, QGenericReturnArgument returnValue, QXT_PROTO_10ARGS(QGenericArgument)) = 0;
+};
+
+#endif
projects / quassel.git / blobdiff