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From "Oliver Heger (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CONFIGURATION-471) CompositeConfiguration delivers value from wrong child
Date Fri, 11 Nov 2011 20:34:51 GMT

    [ https://issues.apache.org/jira/browse/CONFIGURATION-471?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13148715#comment-13148715
] 

Oliver Heger commented on CONFIGURATION-471:
--------------------------------------------

This behavior is indeed inconsistent.

>From looking at the code, the result is caused by the fact that the inMemoryConfiguration
is always stored at the end of the list of managed configurations. Adding of the user configuration
in your second example actually does not have any effect because this configuration is already
contained (as inMemoryConfiguration). So the order of the configurations is reverse to the
desired one. This implementation detail and its consequences are not documented.

I assume, the original authors of CompositeConfiguration did not intend that a single configuration
could be used as both child configuration and inMemoryConfiguration. I am not sure how to
proceed. In any case, documentation should be improved. However, changing the behavior of
CompositeConfiguration in this respect might break existing code.

Thinking about a workaround, would it be possible to use the default inMemoryConfiguration
and register an event listener at it which just copies all changes to the user configuration?
Of course, this means more effort.
                
> CompositeConfiguration delivers value from wrong child
> ------------------------------------------------------
>
>                 Key: CONFIGURATION-471
>                 URL: https://issues.apache.org/jira/browse/CONFIGURATION-471
>             Project: Commons Configuration
>          Issue Type: Bug
>          Components: File reloading
>    Affects Versions: 1.7
>            Reporter: Joerg Wesely
>
> I create a composite configuration with two PropertyConfigurations: a user configuration
and a default configuration, with the userConfiguration as inMemoryConfiguration.
> If both configurations contain the same key, the value from defaultConfiguration is returned
although the user configuration was added first. If no inMemoryConfiguration is specified,
it's working ok:
> Configuration defaultConf = new PropertiesConfiguration();
> defaultConf.addProperty("prop1", "fromDefaultConfig");
>     	
> Configuration userConf = new PropertiesConfiguration();
> userConf.addProperty("prop1", "fromUserConfig");
>     	
> CompositeConfiguration noMemoryConfig = new CompositeConfiguration();
> noMemoryConfig.addConfiguration(userConf);
> noMemoryConfig.addConfiguration(defaultConf);
> System.out.println("noMemoryConfig: " + noMemoryConfig.getString("prop1")); // Shows
"fromUserConfig" 
>     	
> CompositeConfiguration withMemoryConfig = new CompositeConfiguration(userConf);
> withMemoryConfig.addConfiguration(userConf);
> withMemoryConfig.addConfiguration(defaultConf);
> System.out.println("withMemoryConfig: " + withMemoryConfig.getString("prop1")); // Shows
"fromDefaultConfig"

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