Can i transform string in template expression or lambda expression in kotlin?

Question

val tm = "x = $"+"x"
val fn: (x: String) -> String = { it -> tm}
val str = fn("This is X!!!")

Need to get

x = This is X!!!

Why?: You can receive templates, for example, from the database PS: or your suggestions

No: the Kotlin string templates are transformed at compile-time into simple concatenation. You need different tools for string templates at runtime. — hotkey
– hotkey, Commented Aug 21, 2017 at 14:39

Lior Bar-On · Accepted Answer · 2017-08-28 09:35:03Z

2

Kotlin templates are evaluated at compile time - so this won't work.

You should use a 3rd party template engine.

Freemarker is such an engine with a format very similar to Kotlin's own templating format:

val tm = "x = \${x}"

fun fn (x: String) : String {
    val t = Template("name", StringReader(tm), Configuration(Configuration.VERSION_2_3_26))
    val out = StringWriter()
    t.process(mapOf("x" to x) ,out)
    return out.toString()
}

println (fn("This is X!!!")) // x = This is X!!!

Two notes:

You won't be able to use "$x" on freeMarker, only "${x}"
$ sign can be escaped in a Kotlin string using \$

edited Aug 28, 2017 at 9:35

answered Aug 21, 2017 at 15:05

Lior Bar-On

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2 Comments

BakaWaii Over a year ago

When will we use it instead of String.format()? They look similar.

Lior Bar-On Over a year ago

String.format() is an alias for java.lang.String.format(format, *args) - it is useful, but it is different. here.

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