Andrew Lamb created ARROW-11882:
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Summary: [Rust] Implement Debug printing "kernel"
Key: ARROW-11882
URL: https://issues.apache.org/jira/browse/ARROW-11882
Project: Apache Arrow
Issue Type: Improvement
Components: Rust
Reporter: Andrew Lamb
[~jorgecarleitao] offered a great way to improve the Debug/Display
implementations for various Array implementations on
https://github.com/apache/arrow/pull/9624#issuecomment-790976766
The only reason we are implementing to_isize/to_usize on NativeType is because
we have a function to represent an array (for Display) that accepts a generic
physical type T, and then tries to convert it to a isize depending on a logical
type (DataType::Date). However, there is already a Many to one relationship
between logical and physical types.
Thus, a solution for this is to have the `Debug` function branch off depending
on the (logical) datatype, implementing the custom string representation
depending on it, instead of having a loop of native type T and then branching
off according to the DataType inside the loop.
I.e. instead of
{code}
for i in ... {
match data_type {
DataType::Date32 => represent array[i] as date
DataType::Int32 => represent array[i] as int
}
}
{code}
imo we should have
{code}
match data_type {
DataType::Date32 => for i in ... {represent array[i] as date}
DataType::Int32 => for i in ... {represent array[i] as int}
}
{code}
i.e. treat the Display as any other "kernel", where behavior is logical, not
physical, type-dependent.
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