Annotations

Of course not all real world examples are as simple as the 'Hello world' example of the previous pages. Sometimes it is necessary to add some extra configuration information for your options. We have chosen not to use separate configuration files for this purpose, but have instead opted for using annotations in the option context class. Annotation syntax can sometimes be a bit verbose, but annotations have the advantage of being a direct part of the application source and need little extra housekeeping.

As a first example, assume you would like the --times option of the 'Hello world!' application also to be known as a short option -t, then you must add an @Option annotation to the setter method in the option context class, as follows:

import be.ugent.twijug.jclops.annotations.Option;
...

@Option(shortName='t')
public void setTimes(int times) {
    this.times = times;
}
            

(Do not forget to also import the annotation class.)

The @Option annotation also has a longName attribute which allows use to override the long option name which was automatically derived from the method name. If you prefer --times-to-repeat, then you write

@Option(shortName='t',longName="times-to-repeat")
public void setTimes(int times) {
    this.times = times;
}
            

although in this particular case the same result could have been obtained by renaming the setter to setTimesToRepeat (note how CamelCase is converted to dash-separated-words).

The @Option annotation can also be used with a method whose name does not begin with set and would therefore not automatically be recognised as an option setter.

@Option(shortName='t',longName="times-to-repeat")
public void initializeRepeatCount(int times) {
    this.times = times;
}
            

(In this case, a longName attribute is obligatory.)

Conversely, you can annotate a setter method with @NotAnOption if you do not want it to be recognised as an option.

@NotAnOption
public void setBorder(Border border) {
    ...
}
            

However, in most cases this indicates that you should be thinking of refactoring your option context class. Option context and application context need not necessarily be represented by the same object.