Jimexist commented on a change in pull request #1734:
URL: https://github.com/apache/arrow-datafusion/pull/1734#discussion_r799970574
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File path: datafusion/src/logical_plan/expr.rs
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@@ -2189,6 +2189,20 @@ pub fn exprlist_to_fields<'a>(
expr.into_iter().map(|e| e.to_field(input_schema)).collect()
}
+/// Calls a named built in function
+/// ```
+/// use datafusion::logical_plan::*;
+///
+/// // create the expression sin(x) < 0.2
+/// let expr = call_builtin_scalar_fn("sin",
vec![col("x")]).unwrap().lt(lit(0.2));
+/// ```
+pub fn call_builtin_scalar_fn(name: impl AsRef<str>, args: Vec<Expr>) ->
Result<Expr> {
+ match name.as_ref().parse::<functions::BuiltinScalarFunction>() {
+ Ok(fun) => Ok(Expr::ScalarFunction { fun, args }),
+ Err(e) => Err(e),
+ }
Review comment:
i wonder if it makes sense to make it a macro rather than a function
call so that nonexisteng built-in functions will be caught during compile time
not runtime
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