How to mimic Scala's Map/Array assignment syntax in my own class

Question

Following is a simple map entry assignment:

scala> var myl = mutable.Map[String,String]()
myl: scala.collection.mutable.Map[String,String] = Map()
myl("abc") = "123"

I would like to mimic that assignment structure in my own class that works with mutable Tuple's. Now, "getting" a value from a Map is achieved via the "apply" method:

e.g mutable.HashMap:

  override def apply(key: A): B = {
    val result = findEntry(key)
    if (result eq null) default(key)
    else result.value
  }

I was not however able to find how the map entry is "set" via myMap("myKey") = "myval". A pointer to the Scala source code to do that would be appreciated. Thanks.

swartzrock · Accepted Answer · 2013-11-10 01:04:48Z

3

The method you want to implement is called update() and takes two parameters, one for the input value passed in parentheses and the other for the assigned value.

class QueryParams {
  var params = ""
  def update(name: String, value: String) { params += s"$name=$value&" }
}

For example:

val p = new QueryParams()
p("q") = "SFO"
p("start") = "10"
p("rows") = "10"
p.params

edited Nov 10, 2013 at 1:04

answered Nov 10, 2013 at 0:34

swartzrock

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1 Comment

WestCoastProjects Over a year ago

Thanks swartzrock, i looked at that method and almost tried it. Will do so now.

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