Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/21193#discussion_r186644321
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
---
@@ -623,8 +624,14 @@ case class Cast(child: Expression, dataType: DataType,
timeZoneId: Option[String
override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
val eval = child.genCode(ctx)
val nullSafeCast = nullSafeCastFunction(child.dataType, dataType, ctx)
+
+ // Below the code comment including `eval.value` and `eval.isNull` is
a trick. It makes the two
+ // expr values are referred by this code block.
ev.copy(code = eval.code +
- castCode(ctx, eval.value, eval.isNull, ev.value, ev.isNull,
dataType, nullSafeCast))
+ code"""
+ // Cast from ${eval.value}, ${eval.isNull}
--- End diff --
In this particular case I think we should not use the string interpolator.
My preferred end game would be that the `CodeGenerator` functions will just
return blocks (or something like that) instead of an opaque strings. That is
definitely something we should do in a follow up, can we for now just manually
create the block?
That being said, if we are going to pick then I'd strong prefer option 2. I
think option 1 is much harder to work with, and is also potentially buggy (what
happens if you get the order wrong).
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