adamreeve commented on issue #40790:
URL: https://github.com/apache/arrow/issues/40790#issuecomment-2019287063
I think this is actually specific to structs. With a `ListArray`, the child
buffer/Array doesn't need to be sliced, the offset just needs to be accounted
for when accessing the value offsets, so slicing a `ListArray` seems to work
fine. Eg. this passes:
```c#
[Fact]
public void TestSliceListArray()
{
const int numRows = 10;
var builder = new ListArray.Builder(new Int32Type());
var valueBuilder = (Int32Array.Builder) builder.ValueBuilder;
for (var rowIdx = 0; rowIdx < numRows; ++rowIdx)
{
builder.Append();
var length = rowIdx % 3;
for (var i = 0; i < length; ++i)
{
valueBuilder.Append(valueBuilder.Length);
}
}
var array = builder.Build();
var slicedArray = (ListArray) array.Slice(2, 4);
Assert.Equal(4, slicedArray.Length);
for (var rowIdx = 0; rowIdx < slicedArray.Length; ++rowIdx)
{
var slicedArrayList =
(IReadOnlyList<int?>)slicedArray.GetSlicedValues(rowIdx);
var sourceArrayList =
(IReadOnlyList<int?>)array.GetSlicedValues(rowIdx + 2);
Assert.Equal(sourceArrayList, slicedArrayList);
}
}
```
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