tustvold commented on code in PR #2902:
URL: https://github.com/apache/arrow-rs/pull/2902#discussion_r1003629274
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arrow-array/src/array/mod.rs:
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@@ -88,6 +88,31 @@ pub trait Array: std::fmt::Debug + Send + Sync {
/// ```
fn as_any(&self) -> &dyn Any;
+ /// Returns the array as [`Any`](std::any::Any) wrapped into an [`Arc`] so
that it can be
+ /// downcasted to a specific implementation without the need for an
unsized reference. This is helpful if you want
+ /// to return a concrete array type.
+ ///
+ /// Note that this conversion may not be possible for all types due to the
`'static` constraint.
+ ///
+ /// # Example:
+ ///
+ /// ```
+ /// # use std::sync::Arc;
+ /// # use arrow_array::{Int32Array, RecordBatch};
+ /// # use arrow_schema::{Schema, Field, DataType, ArrowError};
+ ///
+ /// let id = Int32Array::from(vec![1, 2, 3, 4, 5]);
+ /// let batch = RecordBatch::try_new(
+ /// Arc::new(Schema::new(vec![Field::new("id", DataType::Int32,
false)])),
+ /// vec![Arc::new(id)]
+ /// ).unwrap();
+ ///
+ /// let int32array = Arc::downcast::<Int32Array>(
+ /// Arc::clone(batch.column(0)).as_any_arc().expect("Failed to create
static Arc")
+ /// ).expect("Failed to downcast");
Review Comment:
Yes, the nature of the way that the downcasting works means that Array is
effectively sealed as there would be no use to implementing it
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