How about adding a new method to File that mimics File.createTemp() but creates a directory instead? I've wanted this a couple of times now:

**
** Create a temporary directory which is guaranteed to be a new, empty
** directory with a unique name.  The dir name will be generated using
** the specified prefix and suffix.  
**
** Examples:
**   File.createTemp("x", "-etc") => `/tmp/x67392-etc/`
**   File.createTemp.deleteOnExit => `/tmp/fan5284/`
**
static File createTempDir(Str prefix := "fan", Str suffix := ".tmp", File? dir := null)

The current workaround is a little awkward:

tempFile := File.createTemp("x-", "-etc")
dirName  := tempFile.name
tempFile.delete
tempDir  := Env.cur.tempDir.createDir(dirName)

That maps to the java.io.File.createTempFile method, I don't think there is any corresponding Java implementation for creating a directory

Oh, you mean this createTempFile() method!

Fair enough, but it doesn't stop Fantom, being a layer on top of Java, from having its own createTempDir method.

It is quite well discussed on StackOverflow in Create a temporary directory in Java with solutions popping up for:

• Google Guava - src
• Apache CommonsIO
• JDK 7