Merge 2995525 into e65fe09

README.md

@@ -175,6 +175,11 @@ which will construct an ARN from the AWS account, region, and this default funct
 
 Credit for the Lambda function script: http://www.spacevatican.org/2015/12/20/cloudformation-nat-gateway/
 
+## Working with Cloudformation Concatenating
+In the CloudFormation DSL, there is support for concatenating strings, parameters, and function calls together to build strings.
+This can get really ugly as they are chained together.
+There is a [string interpolator](http://monsantoco.github.io/cloudformation-template-generator/latest/api/#com.monsanto.arch.cloudformation.model.package$$AwsStringInterpolator) to make this easier.
+
 ## Releasing
 
 This project uses the sbt release plugin.  After the changes you want to

src/main/scala/com/monsanto/arch/cloudformation/model.scala

@@ -135,7 +135,24 @@ package object model {
 
   implicit def parameter2TokenString(parameter : StringParameter) : Token[String] = ParameterRef(parameter)
 
-  implicit class AwsToken(val sc: StringContext) extends AnyVal {
+  /**
+    * Provides a string interpolator to assist in the concatenation of
+    *
+    * The following:
+    * {{{
+    *  import com.monsanto.arch.cloudformation.model._
+    *
+    *  val param = ParameterRef(StringParameter("that"))
+    *  val fun = aws"test\$param"
+    * }}}
+    *
+    * Will generate the following FunctionCall definition:
+    * {{{
+    *  FunctionCallToken(`Fn::Join`("", Seq(StringToken("test"), param)))
+    * }}}
+    *
+    */
+  implicit class AwsStringInterpolator(val sc: StringContext) extends AnyVal {
 
     def aws(tokens: Token[String]*) = AwsStringInterpolation(sc, tokens)