| <!DOCTYPE html |
| PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "../xhtml1-strict.dtd"> |
| <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> |
| <link rel="stylesheet" type="text/css" href="../css/ot.css" /> |
| <link rel="stylesheet" type="text/css" href="../css/otjld.css" /> |
| <title>OT/J Language Definition v1.3.1</title> |
| </head> |
| <body class="otdt"> |
| <div id="content"> |
| <table class="nav"> |
| <tr> |
| <td class="back"><a id="top"></a></td> |
| <td class="top"><a href="index.html" rel="contents">↑ Table of Contents ↑</a></td> |
| <td class="next"><a href="s7.2.html" rel="next">§7.2 Confined roles >></a></td> |
| </tr> |
| </table> |
| <div class="breadcrumb"><a class="nav" href="s7.html" rel="section">§7 Role Encapsulation</a></div> |
| <div class="sect depth2" id="s7.1"> |
| <h2 class="sect">§7.1 Opaque roles<a class="img" href="s7.1.html" |
| title="PermaLink to §7.1 Opaque roles"><img style="vertical-align:text-top;margin-left:5px;" src="../images/permalink.png" |
| alt="" /></a></h2> |
| <p>The purpose of the two <code>IConfined</code> interfaces (see <a href="s6.2.a.html" |
| title="§6.2.(a) Interfaces for role encapsulation" |
| class="sect">§6.2.(a)</a>) is to define |
| <strong>opaque roles</strong>: Any role implementing <code>IConfined</code> |
| can be externalized using this type, such that external clients |
| cannot access any features of the role. The type <code>IConfined</code> |
| exposes no features and references of this type cannot be widened |
| to any type not even to <code>java.lang.Object</code>. |
| <br /> |
| If the actual role type is furthermore invisible outside the team |
| (by not declaring it <code>public</code>), it is perfectly safe to externalize |
| such roles using type <code>IConfined</code> (which is a public interface) |
| and pass them back to the owning team. The encapsulation |
| of the team is in no way breached by externalizing opaque roles, |
| which can only be used as a handle into internal state of the team. |
| |
| </p> |
| <p>The difference between the two mentioned interfaces is that |
| <code>ITeam.IConfined</code> requires to use this type or any subtype |
| as externalized role. Such a reference contains the information of |
| the enclosing team. Even stricter control can be imposed using the |
| regular interface <code>IConfined</code>. Here not even team membership |
| is visible to clients using a reference of this type. |
| |
| </p> |
| </div> |
| <table class="nav"> |
| <tr> |
| <td class="back"></td> |
| <td class="top"><a href="index.html" rel="contents">↑ Table of Contents ↑</a></td> |
| <td class="next"><a href="s7.2.html" rel="next">§7.2 Confined roles >></a></td> |
| </tr> |
| </table> |
| <div class="breadcrumb"><a class="nav" href="s7.html" rel="section">§7 Role Encapsulation</a></div> |
| </div> |
| <div id="footer"> |
| <hr /><a class="w3c img" href="http://jigsaw.w3.org/css-validator/check/referer" |
| shape="rect"><img src="../images/valid-css2-blue.png" alt="Valid CSS!" height="31" width="88" /></a><a class="w3c img" href="http://validator.w3.org/check?uri=referer" shape="rect"><img src="../images/valid-xhtml10-blue.png" alt="Valid XHTML 1.0 Strict" height="31" |
| width="88" /></a><address>© Stephan Herrmann, Christine Hundt, Marco Mosconi</address> |
| OT/J version 1.3.1 — last modified: 2013-05-28 |
| </div> |
| </body> |
| </html> |