How can I use an implicit function with two parameters (Scala)?

Question

I've tried this two options:

object DSChecker {
  implicit def checkImplFunction(dataset: Dataset[Row], config:Config): Checker = new Checker (dataset, config)
}

and

object DSChecker {
  implicit def checkImplFunction(dataset: Dataset[Row])(implicit config:Config): Checker = new Checker (dataset, config)
}

They compile, but the problem is when I need two use them.

I've tried also multiple combinations, but they don't compile... (evalDifferences is a "normal" function inside clas Checker)

//Whithout implicit args in implicit function
import DSChecker._
(df1, difConfig).evalDifferences(df2)

or

// With config as implicit arg in implicit funciton
import DSChecker._
df1.evalDifferences(df2)

The problem is always the same... the compilator doesn't find "evalDifferences" method.

Can someone help me?

Sounds like you might be looking for an extension method instead. — Gaël J
– Gaël J, Commented Jan 5, 2022 at 12:21

Gaël J · Accepted Answer · 2022-01-05 18:36:39Z

3

In your case, I think extension method fits better:

object DSChecker {
  implicit class DfExtension(df: Dataframe) {
    def checker(implicit config: Config) = {
      new Checker(df, config)
    }
  }
}

df1.checker.evalDifferences(df2)

You can also expose evalDifferences directly as extension method.

answered Jan 5, 2022 at 18:36

Gaël J

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Comments

gianluca aguzzi · Accepted Answer · 2022-01-05 11:58:33Z

1

Try with Tuple:

object DSChecker {
  implicit def checkImplFunction(data: (Dataset[Row], Config)): Checker = new Checker (data._1, data._2)
}

Then, this should work:

//Whithout implicit args in implicit function
import DSChecker._
(df1, difConfig).evalDifferences(df2)

answered Jan 5, 2022 at 11:58

gianluca aguzzi

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