yyy1000 commented on code in PR #8985:
URL: https://github.com/apache/arrow-datafusion/pull/8985#discussion_r1483898980
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datafusion/expr/src/udf.rs:
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@@ -249,6 +261,22 @@ pub trait ScalarUDFImpl: Debug + Send + Sync {
/// the arguments
fn return_type(&self, arg_types: &[DataType]) -> Result<DataType>;
+ /// What [`DataType`] will be returned by this function, given the types of
+ /// the expr arguments
+ fn return_type_from_exprs(
Review Comment:
This works well on my side. Thanks!
Another question for me is, how can user implement `return_type_from_exprs`
when using `schema`. For example,
`arg_exprs.get(take_idx).unwrap().get_type(schema)` will lead an error
> the size for values of type `dyn ExprSchema` cannot be known at
compilation time
> the trait `Sized` is not implemented for `dyn ExprSchema`
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