Add a variable to a class instance at runtime: Difference between revisions

=={{header|Wren}}==

Although Wren is dynamically typed, it is not possible to add new variables (or fields as we prefer to call them) to a class at run time. We therefore follow the example of some of the other languages here and use a map field instead.

<lang ecmascript>import "io" for Stdin, Stdout

class Birds {

construct new(userFields) {

_userFields = userFields

}

userFields { _userFields }

}

var userFields = {}

System.print("Enter three fields to add to the Birds class:")

for (i in 0..2) {

System.write("\n name : ")

Stdout.flush()

var name = Stdin.readLine()

System.write(" value: ")

Stdout.flush()

var value = Num.fromString(Stdin.readLine())

userFields[name] = value

}

var birds = Birds.new(userFields)

System.print("\nYour fields are:\n")

for (kv in birds.userFields) {

System.print(" %(kv.key) = %(kv.value)")

}</lang>

{{out}}

Sample session:

<pre>

Enter three fields to add to the Birds class:

name : finch

value: 6

name : magpie

value: 7

name : wren

value: 8

Your fields are:

finch = 6

magpie = 7

wren = 8

</pre>