A toggle is a small pin or rod pushed transversely through a loop, eye, or hole in order to bind it temporarily. It is used to fasten a rope, chain, etc. A toggle is also a type of switch which can be turned to change its position. For example, a switch which controls the lights in an aircraft can be toggled to change from a full beam to a spot light. In software a toggle is typically represented by an icon that is either ON or OFF. It can be switched by pressing on the icon or by using a keyboard command. The word toggle can also be applied to verbs such as tog*gle – to move or shift from one function to another.
The design of a toggle should be simple. It should clearly display the current state of the control by utilizing a high-contrast color (such as red for on or green for off). A clear label which explains what the toggle does is also important. Some teams prefer to use a toggle which looks like a slider in order to avoid confusion with other types of controls such as radio buttons or checkboxes.
A common approach to managing toggle configuration is to hardcode it into static files. This can become cumbersome once you reach a certain scale of deployments. In addition it can often require manual re-deployment of code to a testing environment in order to change a toggle’s configuration. Savvy teams try to limit the number of toggles they introduce and are proactive in removing them once they have been tested. Some teams even put “expiration dates” on their toggles which will fail a test (or possibly even stop a process) if the flag is still present after the expiration date.
