Value Raw is not a member of String (weird error in scala)

Today I was working on a pretty simple system, it involved using the routes of a PlayFramework application to decide the format of the view. Specifically, visiting a resource with a url ending in .html would result in an HTML page being rendered, and similarly with XML.

In addition to the type of data being display, the way it was displayed, or its template, also could change according to a url. For example, displaying a mobile view vs a desktop view, a table vs a list view, a view without any images or style, one with bootstrap... (you get the picture).

But while writing up some error handling code I ran into a really odd error message:

"value raw is not a member of a String"

[error] /path/app/views/common/templateNotFound.scala.xml:4: value raw is not a member of String
[error] 	<Message>The template or the format does exist</Message>
[error] 	                      ^
[error] one error found
[error] (compile:compile) Compilation failed

The offending code was this rather innocuous view:

@(template: String, format: String) 
<?xml version="1.0" encoding="utf-8"?>
<ViewError>
	<Message>The template or the format does exist</Message>
	<Template>@template</Template>
	<Format>@format</Format>
</ViewError>

Nothing about this code immediately jumped out to me as horribly incorrect, and I confused myself some more by removing parts, seeing the same error message, placing them back in, changing the file name, turning sbt on and off. And in general, scratching my head.

After about 5 or so minutes of this, I became suspicious of my variable names. Having read the book Scala Puzzlers, I knew that sometimes the compiler can do some really funny stuff. Since my view is essentially one giant XML literal, I guessed that maybe something was being interpolated or resolved in an odd way. I made the slight change:

@(badTemplate: String, badFormat: String) 
<?xml version="1.0" encoding="utf-8"?>
<ViewError>
	<Message>The template or the format does exist</Message>
	<Template>@badTemplate</Template>
	<Format>@badFormat</Format>
</ViewError>

Saved the file and let sbt ~compile catch it and sure enough:

[info] Compiling 1 Scala source to /path/target/scala-2.10/classes...
[success] Total time: 14 s, completed Apr 27, 2015 11:45:50 PM

Hope this helps someone out there!