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kotlinlang

How can I write a lambda with a receiver such that I can write the following style DSL ```createHttpServer {
            options = myServerOptionsObjectVariableFromAboveSomewhere
            port = 8080
        }``` which should run effectively `vertx().createHttpServer(options).listen(port)`?

you should be in <#C1NH36VV0|vertx> for vertx-specific help

the general Kotlin answer to this question is a function that takes `ClassWithOptionsAndPortProperties.() -&gt; Unit`

which you can use to apply those settings to your new http server instance and then return it

Its not a vertx specific thing - I cannot figure out how to send params from the lambda into the function in this case the options and 8080

```fun httpServer(f: Vertx.() -&gt; Unit) {
    Vertx.vertx().createHttpServer(options).listen(port)
}```

options and port are undefined -- how do i pass them?

well, I mean, if options and port are undefined on the `Vertx` object, then you’ll have to write some kind of adapter or builder to translate the parameters you want to accept to the according ones on your end result type

if you only work with properties defined on Vertx, you can do something like `Vertx.vertx().apply(f)` where `f` is your config function

but if you’re looking to build a more DSL-like configuration around the vertx object, you’ll want to maybe write an intermediary `VertexConfig` class you can use

might resemble something like this:

```
class VertxConfig {
  var port: Short = 0
  lateinit var options: VertxOptions
}

fun createHttpServer(block: VertxConfig.() -&gt; Unit): Vertx {
  val config = VertxConfig().apply(block)
  return Vertx.vertx()
      .createHttpServer(config.options)
      .listen(config.port)
}

// usage
createHttpServer {
  port = 8080
  options = serverOptions
}
```