title: One way binding in Angular Directive
body: <p>How do I use one way binding in an angular directive? I couldn't find a simple, easy example on this, and the docs aren't exactly easy to follow either:</p>
  
  <blockquote>
    <p>&amp; or &amp;attr - provides a way to execute an expression in the context of
    the parent scope. If no attr name is specified then the attribute name
    is assumed to be the same as the local name. Given  and widget definition of scope: {
    localFn:'&amp;myAttr' }, then isolate scope property localFn will point to
    a function wrapper for the count = count + value expression. Often
    it's desirable to pass data from the isolated scope via an expression
    to the parent scope, this can be done by passing a map of local
    variable names and values into the expression wrapper fn. For example,
    if the expression is increment(amount) then we can specify the amount
    value by calling the localFn as localFn({amount: 22}).</p>
  </blockquote>