thorfour opened a new pull request, #36365:
URL: https://github.com/apache/arrow/pull/36365
Expose the number of fields in a schema for iteration over fields.
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### Rationale for this change
Previously if one wanted to iterate over the fields in the schema you would
call the `Fields()` function and just iterate over the slice. However, due to
[this
commit](https://github.com/rtpsw/arrow/commit/802674b73c94c84388a6775b424ebe4f6e04274e)
there is now an allocation and copy that happens when that's called. So to
iterate over the fields without allocations one now must use the `Field(i int)`
method; however that means a user must already know exactly how many fields are
in the schema which isn't possible today.
This adds a simple `NumFields() int` method that returns the number of
fields in a schema to allow a user to iterate over all the fields without
having to copy them.
### What changes are included in this PR?
Single function added `NumFields() int` to schema
### Are these changes tested?
N/A
### Are there any user-facing changes?
Yes this is a new API
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