[jira] [Commented] (CONFIGURATION-753) Handling of interpolation is inconsistent

["Yuji Konishi (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CONFIGURATION-753?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16925602#comment-16925602 ] 

Yuji Konishi commented on CONFIGURATION-753:
--------------------------------------------

This is "First value only".

----
{code:java}
public class Demo {
	public static void main(String[] args) {
		Parameters params = new Parameters();
		FileBasedConfigurationBuilder<FileBasedConfiguration> builder = new FileBasedConfigurationBuilder<FileBasedConfiguration>(
				MyPropertiesConfiguration.class).configure(params.fileBased().setFileName("/tmp/test.properties"));
		try {
			FileBasedConfiguration config = builder.getConfiguration();
			System.out.println(config.getString("foo.one"));
			System.out.println(config.getString("foo.two"));
		} catch (ConfigurationException cex) {
			cex.printStackTrace();
		}
	}
}
{code}
----
{code:java}
public class MyPropertiesConfiguration extends PropertiesConfiguration {
	@Override
	protected void addPropertyDirect(final String key, final Object value)
	{
	    final Object previousValue = getPropertyInternal(key);

	    if (previousValue == null)
	    {
	        super.addPropertyDirect(key, value);
	    }    	
	}	
}
{code}
----



> Handling of interpolation is inconsistent
> -----------------------------------------
>
>                 Key: CONFIGURATION-753
>                 URL: https://issues.apache.org/jira/browse/CONFIGURATION-753
>             Project: Commons Configuration
>          Issue Type: Bug
>          Components: Interpolation
>    Affects Versions: 2.5
>         Environment: Java 8, Configurations2 2.5
>            Reporter: Peter
>            Priority: Major
>         Attachments: test.properties
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> If a key is repeated in a configuration and then used in an interpolation elsewhere, the behaviour is inconsistent. There are other tickets/discussions about whether it should just pick the first value or not, but I don't think it should do both.
> {code:java|title=/tmp/test.properties}
> abc = hello
> abc = world
> foo.one = ${abc}
> foo.two = prefix ${abc} suffix
> {code}
> {code:java|title=Demo.java (main)}
> Parameters params = new Parameters();
> FileBasedConfigurationBuilder<FileBasedConfiguration> builder = new FileBasedConfigurationBuilder<FileBasedConfiguration>(PropertiesConfiguration.class)
>     .configure(params.fileBased()
>         .setFileName("/tmp/test.properties")
>       );
> try {
>     FileBasedConfiguration config = builder.getConfiguration();
>     System.out.println(config.getString("foo.one"));
>     System.out.println(config.getString("foo.two"));
> } catch (ConfigurationException cex) {
>     // pass
> }
> {code}
> The output from the above is
> {noformat}
> hello 
> prefix [hello, world] suffix
> {noformat}
> In the first case, only the first value is being matched, in the second both values (and [, ]) are used.
> I'd expect the output to either be
> {noformat:title=First value only}
> hello
> prefix hello suffix
> {noformat}
> or
> {noformat:title=Both values used}
> [hello, world]
> prefix [hello, world] suffix
> {noformat}
> I can work around whichever style is chosen but think it'd be much more intuitive if both cases were handled the same.



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