Qt Signal Slot Performance
Qt Signal Slot Thread Safe List

When building with Qt, the Moc keywords signals and slots are defined using preprocessor macros, causing programs using Boost.Signals and Qt together to fail to compile.

For Qt 4.1 and later, This behavior can be turned off in Qt on a per-project or per-file basis with the no_keywords option. This works with out-of-the-box builds of Boost and Qt. You do not need to re-configure, re-build, or duplicate existing libraries. For a project where you want to use both Boost.Signals and Qt Signals and Slots, the relevant part of your .pro file might look like this:

Now you can mix Boost.Signals and Qt Signals and Slots in the same files, and even within the same class or function. You will have to use the upper-case versions of Qt macros in your own code. See the article A Deeper Look at Signals and Slots [off-site] for more complete examples and a survey of the strengths of the two systems.

QObjects are one of the fundamental building blocks of Qt applications. QObjects provide memory management, advanced event handling, and signals and slots: a devious mechanism to allow communication between QObjects and modules in a thread-safe manner, while allowing your system to remain loosely coupled and flexible. Connect the signals to the GUI thread's slots using queued signal/slot connections. Mutexes can be used to make a method thread safe. Most Qt methods aren't thread safe because there is always a performance penalty when using mutexes. It isn't always possible to lock and unlock a mutex in a method. Sometimes the need to lock spans several. The Qt Signals And Slots Thread Safe list is updated continuously to ensure you get the Qt Signals And Slots Thread Safe latest bonuses available each time you drop in. Free Spins-More Details Less Details. January 7, 2018. Read our full review. January 13, 2018.

Older versions of Qt did not provide a reliable mechanism for avoiding these unfriendly, all lower-case `keyword'-like macros. Although this is a problem with Qt and not Boost.Signals, a user can use the two systems together with a little extra effort. There are two ways to do this:

Qt Signal Slot Performance

The first way involves defining the BOOST_SIGNALS_NAMESPACE macro to some other identifier (e.g., signalslib) when building and using the Boost.Signals library. Then the namespace of the Boost.Signals library will be boost::BOOST_SIGNALS_NAMESPACE instead of boost::signals. To retain the original namespace name in translation units that do not interact with Qt, you can use a namespace alias:

The second way, provided by Frank Hess and improved by Niels Dekker, involves creating a header signalslib.hpp that contains the following code:

Qt Signal Slot Thread Safe List

Use this header to include the Boost library, then refer to it in the namespace boost::signalslib. This option is often preferable to the first option because it can be used without recompiling the Signals library binary.