[CONFIGURATION-753] Handling of interpolation is inconsistent

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5
• Fix Version/s: 2.8.0
• Component/s: Interpolation

Environment

Java 8, Configurations2 2.5

• Assignee: Matt Juntunen
• Reporter: Peter
• Created: 15/Aug/19 16:27
• Updated: 04/Jul/22 15:06
• Resolved: 20/May/22 03:13

Description

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.

/tmp/test.properties

abc = hello
abc = world
foo.one = ${abc}
foo.two = prefix ${abc} suffix

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
}

The output from the above is

hello 
prefix [hello, world] suffix

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

First value only

hello
prefix hello suffix

or

Both values used

[hello, world]
prefix [hello, world] suffix

I can work around whichever style is chosen but think it'd be much more intuitive if both cases were handled the same.

Issue Links

• links to: GitHub Pull Request #32
• links to: GitHub Pull Request #181