config/NEWS.md

0.NEXT.0: Sometime

• supports self-referential substitutions, such as path=${path}":/bin", by "looking backward" to the previous value of path
• supports concatenating arrays and merging objects within a single value. So you can do path=${path} [ "/bin" ] for example. See README and spec for more details.
• supports += where path+="/bin" expands to path=${?path} [ "/bin" ]
• supports include url("http://example.com/"), include file("/my/file.conf"), and include classpath("whatever"). This syntax forces treatment as URL, file, or classpath resource.
• supports include "http://example.com/whatever.conf" (if an include is a valid URL, it's loaded as such). This is incompatible with prior versions, if you have a filename that is also a valid URL, it would have loaded previously but now it will not. Use the include file("") syntax to force treatment as a file.
• class loaders are now recursively inherited through include statements; previously, even if you set a custom class loader when parsing a file, it would not be used for parsing a classpath resource included from the file.
• parseString() and parseReader() now support include statements in the parsed string or reader
• in -Dconfig.resource=name, name can start with a "/" or not, doesn't matter
• if you implement ConfigIncluder, you should most likely also implement ConfigIncluderFile, ConfigIncluderURL, and ConfigIncluderClasspath. You should also use ConfigIncludeContext.parseOptions() if appropriate.
• cycles in include statements (self-includes) are now detected and result in a nicer error instead of stack overflow
• the serialization format has changed for a Config that has not had resolve() called on it. The library can still deserialize the old format, but old versions of the library will not be able to deserialize the new format. Serializing unresolved Config is probably a bad idea anyway and maybe shouldn't even be supported, but keeping it for back compat.
• since 0.3.0, there is an obscure incompatible semantic change in that self-referential substitutions where the cycle could be broken by partially resolving the object now "look backward" and may fail to resolve. This is not incompatible with the version included in Play/Akka 2.0 because in that version this obscure case just threw an exception. But in 0.3.0 there were cases that worked that now work differently. You are very unlikely to be affected by this.

0.3.0: March 1, 2012

• ConfigFactory methods now use the thread's context class loader by default, and have overloads so you can specify a class loader. Because jars may come with "reference.conf" in the jar, a config must always be loaded with the same class loader as the jar using the config.
• ConfigValue instances are now serializable
• new methods ConfigObject.withoutKey, ConfigObject.withOnlyKey, Config.withoutPath, Config.withOnlyPath allow subsetting configs more easily.
• better handle complex interdependent substitutions (the ${foo} syntax) without getting confused; just about anything that makes conceptual sense should now work. Only inherently circular config files should fail.
• some minor documentation fixes.