<form name="test_form" ng-controller="TestCtrl">
<input type="checkbox" name="a" ng-model="a" id="check" ng-checking="say()"/>
<label for="check">{{ a }}</label>
</form>
var app = angular.module('Demo',[]);
app.directive('ngChecking',function(){
var fun1 = function(element,attrs){
return function(scope,iElement,iAttrs){
scope.$watch('a',function(){
if(iElement[0].checked){
if(iAttrs['ngChecking']){   
var fun = iAttrs['ngChecking'].match(/\w+()/g);
scope[fun[0]]();
}
}
})
}
}
return {
compile:fun1,
restrict:'AE'
}
})
app.controller('TestCtrl',function($scope){
$scope.say = function(){
alert(123)
}
});
angular.bootstrap(document,['Demo']);