[jira] [Commented] (CONFIGURATION-508) Add generic get method to convert config property to any object

["Oliver Heger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CONFIGURATION-508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13463160#comment-13463160 ] 

Oliver Heger commented on CONFIGURATION-508:
--------------------------------------------

We already have similar functionality in {{DataConfiguration}} which can be used as a wrapper around a standard {{Configuration}} object providing enhanced access methods. The methods even try to do some simple data type conversions. However, the whole concept could certainly be extended by a customizable converter framework. Please have a look whether these methods fit your needs.

I like your detailed description of the process for creating an object of a given target class. If this is a standard algorithm for creating an instance of class A based on string input (or maybe even on an arbitrary type B), maybe it is a candidate for being included into Commons Lang, for instance in {{ObjectUtils}}?
                
> Add generic get method to convert config property to any object
> ---------------------------------------------------------------
>
>                 Key: CONFIGURATION-508
>                 URL: https://issues.apache.org/jira/browse/CONFIGURATION-508
>             Project: Commons Configuration
>          Issue Type: Improvement
>          Components: Type conversion
>    Affects Versions: 1.9
>            Reporter: Matt Bertolini
>              Labels: configuration, constructor, conversion, convert, generic, property, static, type, valueof
>
> Now that commons configuration requires java 5.0+, I think we should consider adding a couple of new generic getter methods that will enable developers to automatically convert the configuration property to the object of their choice. I envision the API looking like the below:
> {code:java}
> public <T> T get(String key, Class<T> clazz);
> public <T> T get(String key, Class<T> clazz, T defaultValue);
> {code}
> The method would perform a five step process:
> # First it would get the string value, post interpolation.
> # Then it would check the given class for the existence of a static "valueOf" method with one String argument. If found, it would invoke that method with the interpolated string value.
> # If no static "valueOf" method is found, it would search for a constructor with one String argument. If that is found, it would construct a new instance of the class passing the interpolated string value.
> # If no constructor or static method is found, it will check if a default value was given, returning it if true.
> # Finally, if no default value is given, it checks to see if throwExceptionOnMissing is set to true. If so, it will throw the exception. If false, it will return null.
> This behavior is similar to how the Spring conversion service works. I believe that this feature would be a great help to developers as many of the values contained in configuration properties often times map over to various model objects.
> I am looking for some feedback on the idea. Let me know your thoughts. Thanks.

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