[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #4916: Improve documentation for ExprVisitor, port simple uses to new walking function

[GitBox <gi...@apache.org>]

alamb commented on code in PR #4916:
URL: https://github.com/apache/arrow-datafusion/pull/4916#discussion_r1070579121


##########
datafusion/expr/src/utils.rs:
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@@ -83,20 +85,16 @@ pub fn grouping_set_to_exprlist(group_expr: &[Expr]) -> Result<Vec<Expr>> {
     }
 }
 
-/// Recursively walk an expression tree, collecting the unique set of column names
+/// Recursively walk an expression tree, collecting the unique set of columns

Review Comment:
   here is a pretty good example of reducing the ceremony required do to a walk of an expr by using `inspect_expr_pre` rather than having to define a visitor explicitly



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