A slot is a normal method, global function, lambda expression, or function object that reacts to a signal.
Qt supports a simple mechanism that allows any class to define its own signals and slots: simply connect any callable target to a signal as a slot. Once connected, the slot is executed whenever the signal is emitted. This is completely independent of the event loop that the GUI uses to control objects.
Connected slots can be synchronously or asynchronously (see below). If a slot is associated with a context it will always be executed synchronously, unless the connection type of that slot is changed.
Exceptions to this rule can be specified by specifying an exec::sync or exec::async enumerator in the connect() method of the signal. Default behavior is to use the connection type of the thread that the context belongs to. pg soft bet termurah
If the slot is a member function of a static class, it will receive the full method name and prototype string of the corresponding signal method. This is to make it easy for the user to match the slot to a signal, especially in cases where the signal signature is unclear.
When a slot is disconnected, it will be removed from the list of connected slots in the same order that it was connected to them. A slot can be deleted either by calling the special disconnect() method on its ancestor signal or by passing a special connection id value to that method.
The connection id value is used for re-connecting the slot to the same signal as well as to reconnect it to another signal when a different ancestor signal has been triggered. When the connection is re-established, it will be invoked in the same order that it was connected to the signal, except for overloads with different argument counts that would result in Qt picking an overload with the higher number of arguments.
A slot can be accessed from multiple threads: cls, dob, ics, jls, ksc, lfs, mws, nod, psg and vdk allow this. However, aco, asg, cps, evl, ics, jls, jos, nes, nls, psg, sss, wnk and yas are mono-thread exclusive.
If a slot is not accessible from a certain thread, it will not be re-connected until the thread is accessible again. Alternatively, the slot can be disabled in that case, which prevents it from being re-connected until the thread is accessible.
The connections can be synchronized: asynchronous slots are not re-connected until the underlying thread is accessible again, but asynchronous slots can be connected to other asynchronous slots. This is useful when a synchronized slot needs to be re-connected to other asynchronous slots, or if the slot has to be re-connected for other reasons.
Some libraries forbid the assignment of an empty slot to an existing instance (s = signal()). aco, asg, cps, dob, evl, ics, jos, nes, nls and psg disallow this, whereas bs2, cps, dob, ics, nod, nls and pss don't.
If you are working with a library that does not have this behavior, consider creating your own signal/slot implementation instead of using the library's version. This will ensure that you are using the same function when triggering the slot, and avoid any potential conflicts.