ant/proposal/sandbox/selectors

Selector API
============

Currently our filesets allow us to select a set of files based on name patterns.
For instance we could create a set of all the files that end with ".java". 
However there are cases when you wish to select files based on their other 
attributes, such as if they are read only or if they are older than a specified 
date etc. 

The selector API is one such mechanism to do this. The selector API will allow 
you to build file sets based on criteria other than name. Some possible criteria 
would be 

Is the file readable? 
Is the file writeable? 
What date was the file modified on? 
What size is the file? 
Does the contents contain the string "magic"? 

If we end up supporting a VFS then we could expand the number of selectors 
considerably. A mock representation that has been proposed before is the 
following. Of course this is subject to change as soon as someone wants to 
tackle this action ;) 

 <include name="**/*.java">
   <selector type="permission" value="r"/>

   <!-- could optionally be directory/or some other system specific features -->
   <selector type="type" value="file"/> 
   <selector type="modify-time" 
             operation="greater-than" 
             value="29th Feb 2003"/>
 </include>