CancellableSourceFunc
typealias CancellableSourceFunc = (cancellable: Cancellable?, <Error class: unknown class>?) -> Boolean
This is the function type of the callback used for the #GSource returned by g_cancellable_source_new().
param
cancellablethe #GCancellableparam
datadata passed in by the user.return it should return false if the source should be removed.