Why would you want to do this? Not sure but a sample here:

[as]var _x = 100;

function a() : void { trace("\t\tCalled from A = _x" + _x + "\n"); }

var b = function (): void { trace("\t\tCalled from B \n"); }

trace("Do a regular B call\n"); b();

trace("Convert B to A\n"); b = a;

trace("B Converted\n"); b(); trace("Do a regular A call\n"); a();[/as]

Result

[as]Do a regular B call

Called from B

Convert B to A

B Converted

Called from A = _x100

Do a regular A call

Called from A = _x100[/as]