Slot is a dynamic placeholder that either waits for content (a passive slot) or calls out for it (an active slot). Slots are managed by scenarios that use an Add Items to Slot action or a targeter to fill the slot with content. Renderers then specify how the content is presented on a Web page.
In hockey, the slot is the area in front of the goaltender and between the face-off circles in the offensive zone. A winger or center can shoot the puck into the slot to create a one-timer, which can be one of the best shots in the game. A well-placed shot from the slot can also deflect off a teammate and go in for a goal.
Psychologists have found that people who play video slots reach a debilitating level of involvement in gambling three times faster than those who play traditional casino games. This can be dangerous, as the National Lampoon’s Vegas Vacation movie demonstrates when Chevy Chase’s character gets gambling fever and loses four cars.
Slot is a Qt feature that lets you write lambda functions that take arguments and return values without needing to call the function’s sender or context. Using slots reduces the number of non-virtual function calls in your code, improving performance. However, emitting a signal connected to a slot incurs the overhead of checking that the receivers are alive and locating the connection object. This may make it slower than calling the receivers directly.