RegisterBinaryCallbackHandler

typedef RegisterBinaryCallbackHandler = R Function(T1, T2) Function(
  Zone self,
  ZoneDelegate parent,
  Zone zone,
  R Function(T1 arg1, T2 arg2) f,
)

The type of a custom Zone.registerBinaryCallback implementation function.

A function used as ZoneSpecification.registerBinaryCallback to specialize the behavior of a new zone.

Receives the Zone that the handler was registered on as self, a delegate forwarding to the handlers of self's parent zone as parent, and the current zone where the error was uncaught as zone, which will have self as a parent zone.

The function f is the function which was passed to the which was passed to the Zone.registerBinaryCallback of zone.

The handler should return either the function f or another function replacing f, typically by wrapping f in a function which does something extra before and after invoking f