c# - PropertyChanged is ignored when Binding to IEnumerable where reference stays the same -

i created minimal example illustrate binding issue. ienumerable<string> newreference gets updated expected. ienumerable<string> samereference not updated, presumably because reference same. raise("samereference"); not enough make wpf update reference.

is there can done make wpf framework revaluate samereference though has same reference?

xaml:

<window x:class="stackoverflow.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         title="mainwindow" height="350" width="525">     <grid background="azure">         <grid.rowdefinitions>             <rowdefinition height="5*"/>             <rowdefinition height="1*"/>         </grid.rowdefinitions>         <grid.columndefinitions>             <columndefinition/>             <columndefinition/>         </grid.columndefinitions>         <button content="update" margin="5" grid.row="1" grid.columnspan="2" click="button_click" />         <listbox itemssource="{binding samereference}" margin="5" />         <listbox itemssource="{binding newreference}" margin="5" grid.column="1" />     </grid> </window> 

xaml.cs:

using system.collections.generic; using system.collections.objectmodel; using system.componentmodel; using system.windows; using system.windows.controls;  namespace stackoverflow {     public partial class mainwindow : window , inotifypropertychanged     {         public list<string> data = new list<string> {  };         public ienumerable<string> samereference { { return data; } } //this returns reference unchanged object         public ienumerable<string> newreference { { return new list<string>(data); } } //this returns reference new object         //observablecollection<string> conventional known not point of question          public event propertychangedeventhandler propertychanged;          private void raise(string propertyname)         {             if(null != propertychanged)             {                 propertychanged(this, new propertychangedeventargs(propertyname));             }         }          public mainwindow()         {             this.datacontext = this;             initializecomponent();         }          private void button_click(object sender, routedeventargs e)         {             data.add("this data.");             raise("samereference"); //successful notify, ignored values             raise("newreference"); //successful notify, processed values         }     } } 

that intentional behavior. if want collections update implement inotifycollectionchanged (or use class does, observablecollection<t>).