Show how to create a Settings class to encapsulate your Config

README.md

@@ -101,6 +101,30 @@ In brief, as shown in the examples:
    format or data source you like with the methods in
    `ConfigValueFactory`.
 
+## Schemas and Validation
+
+There isn't a schema language or anything like that. However, two
+suggested tools are:
+
+ - use the
+   [checkValid() method](http://typesafehub.github.com/config/latest/api/com/typesafe/config/Config.html#checkValid%28com.typesafe.config.Config,%20java.lang.String...%29)
+ - access your config through a Settings class with a non-lazy
+   field for each setting, and instantiate it on startup
+
+In Scala, a Settings class might look like:
+
+    class Settings(config: Config) {
+
+        // validate vs. reference.conf
+        config.checkValid(ConfigFactory.defaultReference(), "simple-lib")
+
+        // non-lazy fields, we want all exceptions at construct time
+        val foo = config.getString("simple-lib.foo")
+        val bar = config.getInt("simple-lib.bar")
+    }
+
+See the examples/ directory for a full compilable program.
+
 ## Standard behavior
 
 The convenience method `ConfigFactory.load()` loads the following

examples/simple-lib/src/main/scala/simplelib/SimpleLib.scala

@@ -23,3 +23,37 @@ class SimpleLibContext(config: Config) {
         println("The setting '" + path + "' is: " + config.getString(path))
     }
 }
+
+// Here is an OPTIONAL alternative way to access settings, which
+// has the advantage of validating fields on startup and avoiding
+// typos. This is redundant with the SimpleLibContext above,
+// in fact we'll show a settings-based context below.
+class SimpleLibSettings(config: Config) {
+
+    // checkValid(), just as in the plain SimpleLibContext
+    config.checkValid(ConfigFactory.defaultReference(), "simple-lib")
+
+    // note that these fields are NOT lazy, because if we're going to
+    // get any exceptions, we want to get them on startup.
+    val foo = config.getString("simple-lib.foo")
+    val hello = config.getString("simple-lib.hello")
+    val whatever = config.getString("simple-lib.whatever")
+}
+
+// This is a different way to do SimpleLibContext, using the
+// SimpleLibSettings class to encapsulate and validate your
+// settings on startup
+class SimpleLibContext2(config: Config) {
+    val settings = new SimpleLibSettings(config)
+
+    def this() {
+        this(ConfigFactory.load())
+    }
+
+    // this is the amazing functionality provided by simple-lib with a Settings class
+    def printSettings() {
+        println("foo=" + settings.foo)
+        println("hello=" + settings.hello)
+        println("whatever=" + settings.whatever)
+    }
+}