Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/377#discussion_r53538246
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java
---
@@ -109,6 +116,16 @@ public int getValue() {
public static FunctionCostCategory getDefault() {
return SIMPLE;
}
+ }
+ /**
+ * The number of argument(s) for a function
+ *
+ * This annotation element tells if the number of argument(s) is fixed
or arbitrary. Most functions are supposed to
+ * have fixed number of argument(s); One of the exceptions is String
Concatenation function (i.e., concat(...)), which
+ * can take as many arguments as users would like.
+ */
+ enum FunctionArgumentNumber {
+ FIXED, VARIABLE
--- End diff --
Even under VARIABLE category, there could be function which takes >=0, >=1,
etc. For instance, I assume concat will take >=2 arguments. 0 or 1 input
should not be valid. Do you have logic to differentiate difference functions?
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