MagicalStrings - Revision history

JaroslavTulach: /* Not in the OSGi Spec! */

2015-02-17T16:46:06Z

Not in the OSGi Spec!

JaroslavTulach at 10:04, 9 May 2010

2010-05-09T10:04:17Z

JaroslavTulach at 20:18, 8 April 2010

2010-04-08T20:18:47Z

JaroslavTulach at 20:16, 8 April 2010

2010-04-08T20:16:00Z

JaroslavTulach at 20:08, 8 April 2010

2010-04-08T20:08:14Z

JaroslavTulach at 20:07, 8 April 2010

2010-04-08T20:07:58Z

JaroslavTulach at 20:06, 8 April 2010

2010-04-08T20:06:13Z

JaroslavTulach: New page: One dirty trick to provide an API which looks incapable, but which people with in-depth knowledge can use to do magical things is to use MagicalStrings. Just define:
2010-04-08T20:05:18Z

New page: One dirty trick to provide an API which looks incapable, but which people with in-depth knowledge can use to do magical things is to use MagicalStrings. Just define: <source lang=...

New page
One dirty trick to provide an [[API]] which looks incapable, but which people with in-depth knowledge can use to do magical things is to use [[MagicalStrings]]. Just define:

<source lang="java">
public void configure(String url);
</source>

and tell people that they can pass in a location of configuration file. So far so good. But then also provide additional [[API]] which, if the string starts with ''purge!'' removes the existing configuration. To make things even more magical, don't mention this in [[Javadoc]] of the method. Can you see how capable [[API]]s you can offer member of your secret [[API]] society?

Recently I faced this while trying to use [[OSGi]] containers effectively. I needed to install a bundle. There is a method installBundle(String url), but it copies the [[JAR]] from the url location to internal cache. That is not really effective in [[Netigso|my case]] and I wanted to tell the container to use the original [[JAR]]. This problem puzzled me for a while. I thought I will have to use some specific container methods. That did not make me happy as [[Netigso]] supports both [[Felix]] and [[Equinox]] and having ''containerisms'' is not really flexible. I did not know what to do - so I started with [[NetbinoxPerformance|slightly arrogant blog]]. Surprisingly that helped!

Tom Watson (a member of [[OSGi]] secret society, imho) [[Talk:NetbinoxPerformance|replied]] and told me that I can just prefix my URL with ''reference:''. Oh, those [[MagicalStrings]]! I was searching for a special method ''installAsReference(String url)'', but it did not come to my mind to use special pseudo URL protocol! How could it, [[Javadoc]] of the method is silent about such possibility. Maybe I should have read the [[OSGi]] spec. But I did. Maybe not that carefully, but it is easy to oversight some [[MagicalStrings]] in hundred page document anyway.

I am going to claim that [[MagicalStrings]] are anti pattern. But on the other hand, they can be quite useful. They increase the value of consultancy! If you create an [[API]] full of [[MagicalStrings]], then you will be payed for helping people to use it (if they get locked in your [[API]]).

[[Category:APIDesignPatterns:Anti]]