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kotlinlang

can you show the code for `missingParamError` and `incorrectPassword`, and what the similarity/differences between them are?

```
object Errors {
    fun missingParam(req: Request, res: Response)
            = generalError(req, res, 400, "missing-param")

    fun invalidPhone(req: Request, res: Response)
            = generalError(req, res, 400, "invalid-phone")

    fun incorrectPin(req: Request, res: Response)
            = generalError(req, res, 400, "incorrect-pin")

    fun badRequest(req: Request, res: Response)
            = generalError(req, res, 400, "general-error")
}

fun generalError(req: Request, res: Response, status: Int, error: String): String {
    return res.redirectTo(req.pathInfo() + "?" + error)
}
```

(there is a bit more stuff in `generalError()`, logging etc)

where do `request`, and `response` come from when you call `missingParamError(request, response)`? Is there an enclosing class you can make the receiver?

i just have simple functions on an object, like 
```
object Controller {
    fun verifyPhone(req: Request, res: Response): String {
        ...
    }
}
```

as <@U3D0A5GP9> mentioned, you won't have access to `Request` or `Response` without using a closure, but then you will lose the reusability so wouldn't be any use to you

the closest I got is by refactoring so that you can pass the Request/Response pair as a receiver:
```
data class ReqResp(val req: Request, val res: Response)

fun verifyPhone(req: Request, res: Response) {
    handle(req, res) {
        // do your handling code
        // else
        error("missing-param")
    }
}

fun handle(req: Request, res: Response, handle:ReqResp.() -&gt; Unit) {
    ReqResp(req, res).handle()
}

fun ReqResp.error(error: String) {
    res.redirectTo(req.pathInfo() + "?" + error)
}
```

pretty neat, but the extra abstraction will probably confuse some people

yes, agreed - if you could arrange it so people could only write `handle` functions it might be more palatable