CODEWITHSUNDEEP
scala
senjin.hajrulahovic
senjin.hajrulahovic

Reputation: 3191

File system class structure in scala

What would be the appropriate way to implement a file system class structure in scala?

I want the Root to be a Directory and to have itself as a parent.

import scala.collection.mutable

sealed trait Entry
class Directory(val parent: Directory, val content: mutable.IndexedSeq[Entry]) extends Entry
class File(val parent: Directory, val content: String) extends Entry
object Root extends Directory(Root, mutable.IndexedSeq[Entry]())

The attempt above results in:

Error:

(23, 31) super constructor cannot be passed a self reference unless parameter is declared by-name object Root extends Directory(Root, IndexedSeq())

Upvotes: 4

Views: 286

Answers (1)

jwvh
jwvh

Reputation: 51271

One thing you could do is create a 2nd trait just for directories.

import scala.collection.mutable.ArrayBuffer  // easier to update

sealed trait Entry
sealed trait Directory extends Entry {
  val parent  :Directory
  val content :ArrayBuffer[Entry]
}

class File(val parent  :Directory
          ,val content :String) extends Entry

class SubDir(val parent  :Directory
            ,val content :ArrayBuffer[Entry]) extends Directory

object Root extends Directory {
  override val parent  :Directory = this
  override val content :ArrayBuffer[Entry] = ArrayBuffer()
}

Now you can create/update directory contents, and the parent of Root is still Root.

Root.content += new File(Root, "name")
Root.content += new SubDir(Root, ArrayBuffer())

Root.parent.parent.parent  //res2: Directory = Root$@294c7935

Upvotes: 1

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