Re: Self-configuring classes
rossum wrote:
On Fri, 03 Aug 2007 14:59:25 -0500, Chris <spam_me_not@goaway.com>
wrote:
This is a general design question.
I'd like a developer to be able to be able to write his own class that
implements one of our interfaces. The developer would then register the
class with our app which would use it. Our app would discover what
configuration parameters the class needed, and then throw up a page in
our UI so an end user could fill them in.
The question is, what is the best way for the class to tell the app what
parameters it requires? Are there any good design patterns for this?
I could use reflection to discover all the setXXX() methods on the
class, but I'm not sure this is flexible enough, plus I don't like
reflection.
JMX sort-of purports to do this kind of thing, but it's kind of ugly as
well. At least it was when I looked at it a couple years ago.
Have you interface include a method to return the required parameters
in some standard format string.
Your app would call this method on the developers class, parse the
returned string and throw up a user form with all the
required/optional parameters as specified.
rossum
Or, same idea but a bit more control, define an interface:
interface ParameterAccepter{
String acceptParameter(String value);
String parameterText();
}
acceptParameter returns null if the value if good, or a String
saying what is wrong with it. parameterText supplies a String you
can use as a label in the GUI and as part of the dialog reporting
an error.
The method in the main interface returns a ParameterAccepter[], null or
length zero if there are no parameters.
You can, if you like, supply some utility methods for conversion and
range checks.
Patricia