title: why does not it work that ng-show with expression?
body: <p>I want to show something when some variate value is -1 with angular,like this:<code>&lt;div ng-show="{{pid==-1}}"&gt;something&lt;/div&gt;</code>,and it does not work.but it works like this :<code>&lt;div ng-show="pid==-1"&gt;something&lt;/div&gt;</code>.why does this happen?    </p>