java needs closures
This blog post is ancient. If it is technical, the information is likely inaccurate, or at least out of date. If it is non-technical, it’s entirely possible that the relevant facts and my own opinions have changed significantly since it was written.
It is only preserved as part of this site’s permanent historical archive.
I’m sure everyone is sick of reading this same rant over and over, but I just had to add more fuel to the fire. I’m attempting to implement access privilege delegation in a JSF application - basically, users can delegate their ability to do “stuff” in our application to other users. I have a backing bean that has several methods that are called by the JSF components, returning whether or not to render that component based on security privileges. Well, I now have to make all of those methods aware of delegation! I have something like this in several methods:
boolean notX = (loggedInUser.isX());<br></br>if (notX) {<br></br> boolean result = false;<br></br> Set delegations = loggedInUser.getDelegations();<br></br> for (Iterator i = delegations.iterator(); i.hasNext();) {<br></br> User delegator = (User) i.next();<br></br> if (delegator.isX()) {<br></br> result = true;<br></br> break;<br></br> }<br></br> }<br></br> return result;<br></br>} else {<br></br> return true;<br></br>}<br></br>
Now, it would be nice if I could extract the contents of that if block into a new method, say “checkDelegations()”. Unfortunately, the isX() that I need to call is different for every method following this pattern. I’d like to be able to pass a function that calls isX() on the delegator into the checkDelegations() method. No dice in Java. Does anyone else have a solution to this problem?