This is a replacement of the QSingleApplication for `Qt5`.
-Keeps the Primary Instance of your Application and kills each subsequent instance.
+Keeps the Primary Instance of your Application and kills each subsequent instances.
+
+**NOTABLE DIFFERENCES OF THIS FORK WITH THE [ORIGINAL VERSION](https://github.com/itay-grudev/SingleApplication)**: Code style, Windows mutex creation and the instanceArguments() signal.
Usage
-----
-The `SingleApplication` class inherits from `QApplication`. Use it as if you are using the `QApplication` class.
+The `SingleApplication` class inherits from whatever `Q[Core|Gui]Application` class you specify in the `*.pro` file. Further usage is similar to use one of the `Q[Core|Gui]Application` classes.
The library uses your `Organization Name` and `Application Name` to set up a `QLocalServer` and a `QSharedMemory` block. The first instance of your Application would check if the shared memory block exists and if not it will start a `QLocalServer` and then listen for connections on it. Each subsequent instance of your application would check if the shared memory block exists and if it does, it will connect to the QLocalServer to notify it that a new instance had been started, after which would terminate the new instance with status code `0`. The Primary Instance, `SingleApplication` would emmit the `showUp()` signal upon detecting that a new instance had been started.
The library uses `stdlib` to terminate the program with the `exit()` function.
Here is an example usage of the library:
```cpp
+// project.pro
+DEFINES += QAPPLICATION_CLASS=QApplication # or whatever app class you want
The SingleApplication class implements a `showUp()` signal. You can bind to that signal to raise your application's window when a new instance had been started.
Note that since `SingleApplication` extends the `QApplication` class you can do the following:
```cpp
-QObject::connect(QApplication::instance(), SIGNAL(showUp()), window, SLOT(raise())); // window is your QWindow instance
Using `QApplication::instance()` is a neat way to get the `SingleApplication` instance at any place in your program.
-Extending from other application classes
------------------------
-
-`SingleApplication` extends from the `QApplication` class by default , but you can easily change that to `QGuiApplication` or `QCoreApplication` with the `QAPPLICATION_CLASS` macro. Define it before the include statement of `singleapplication.h` or change the default value in the file.
-__Example:__
+The `Instance Arguments` signal
+------------------------
+This fork of SingleApplication also implements a `instanceArguments(QStringList)` signal. You can connect this signal to receive any arguments that might've been passed to the now-dead instance of the application.
-```cpp
-#define QAPPLICATION_CLASS QCoreApplication
-```
Implementation
--------------
The library is implemented with a QSharedMemory block which is thread safe and guarantees a race condition will not occur. It also uses a QLocalSocket to notify the main process that a new instance had been spawned and thus invoke the `showUp()` signal.
To handle an issue on `*nix` systems, where the operating system owns the shared memory block and if the program crashes the memory remains untouched, the library binds to the following signals and closes the program with error code = `128 + signum` where signum is the number representation of the signal listed below. Handling the signal is required in order to safely delete the `QSharedMemory` block.
* `SIGINT ` - `2`
* `SIGILL ` - `4`
* `SIGABRT` - `6`
* `SIGFPE ` - `8`
* `SIGSEGV` - `11`
* `SIGTERM` - `15`
License
-------
This library and it's supporting documentation are released under `The MIT License (MIT)`.