For comments.

Author: viirya

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala

@@ -89,27 +89,19 @@ abstract class UnaryMathExpression(f: Double => Double, name: String)
   }
 }
 
-/**
- * A binary expression specifically for math functions that take two input parameters and
- * returns one output value.
- * @param name The short name of the function
- */
-abstract class AbstractBinaryMathExpression[T, U, V](name: String)
-  extends BinaryExpression with Serializable with ExpectsInputTypes { self: Product =>
-  override def toString: String = s"$name($left, $right)"
-}
-
 /**
  * A binary expression specifically for math functions that take two `Double`s as input and returns
  * a `Double`.
  * @param f The math function.
  * @param name The short name of the function
  */
 abstract class BinaryMathExpression(f: (Double, Double) => Double, name: String)
-  extends AbstractBinaryMathExpression[Double, Double, Double](name) { self: Product =>
+  extends BinaryExpression with Serializable with ExpectsInputTypes { self: Product =>
 
   override def expectedChildTypes: Seq[DataType] = Seq(DoubleType, DoubleType)
 
+  override def toString: String = s"$name($left, $right)"
+
   override def dataType: DataType = DoubleType
 
   override def eval(input: InternalRow): Any = {
@@ -222,7 +214,7 @@ case class ToRadians(child: Expression) extends UnaryMathExpression(math.toRadia
 
 
 case class Atan2(left: Expression, right: Expression)
-  extends AbstractBinaryMathExpression("ATAN2") {
+  extends BinaryMathExpression(math.atan2, "ATAN2") {
   override def expectedChildTypes: Seq[DataType] = Seq(DoubleType, DoubleType)
   override def dataType: DataType = DoubleType
 

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -1097,7 +1097,7 @@ object functions {
    * @group math_funcs
    * @since 1.4.0
    */
-  def log(base: Double, a: String): Column = log(base, Column(a))
+  def log(base: Double, columnName: String): Column = log(base, Column(columnName))
 
   /**
    * Computes the logarithm of the given value in base 10.