Can you use a custom string interpolation character in Scala?

user_1241878 0
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Scala's string interpolation is pretty straight forward to use:

val user = "Bob"
val message = s"Hello, $user"
//Hello, Bob

For string blocks containing lots of financial data, these normally need double escaping, however (which for large blocks, such as test data, might get long):

val user = "Mary"
val message = s"Balance owing for $user is $100"
//error: invalid string interpolation $1, expected: $$, $identifier or ${expression}
//error: unclosed string literal
val message = s"Balance owing for $user is $$100"
//Balance owing for Mary is $100

Is it possible to use a different interpolation character to avoid the double escape?

val characterA = "Randolph"
val characterB = "Mortimer"
val family = "Duke"
val film = "Trading Places"
val outcome = "wagered"
val message = at"Your property was @{outcome} for $1 by brothers @{characterA} and @{characterB} @{family}"
//Your property was wagered for $1 by brothers Randolph and Mortimer Duke
string-interpolation interpolation scala string
2 Answers

Is it possible to use a different interpolation character to avoid the double escape?

$ is part of Scala syntax, however it is at least possible to define custom string interpolation along the lines

scala> implicit class DollarSignInterpolation(val sc: StringContext) {
     |   def usd(args: Any*): String =
     |     sc.s(args:_*).replace("USD", "$")
     | }
class DollarSignInterpolation

scala> val user = "Mary"
val user: String = Mary

scala> usd"""Balance owing for $user is USD100"""
val res0: String = Balance owing for Mary is $100
user_52050220

You can always use the format method:

val message = "Your property was %s for 1$ by brothers %s and %s %s"
println(message.format("actual outcome", "actual characterA", "actual characterB", "actual family"))
user_23592270
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