[GitHub] [arrow] kevingurney commented on a diff in pull request #35655: GH-35598: [MATLAB] Add a public `Valid` property to to the `MATLAB arrow.array.` classes to query Null values (i.e. validity bitmap support)

["kevingurney (via GitHub)" <gi...@apache.org>]

kevingurney commented on code in PR #35655:
URL: https://github.com/apache/arrow/pull/35655#discussion_r1205840940


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matlab/src/cpp/arrow/matlab/array/proxy/numeric_array.h:
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@@ -26,11 +26,19 @@
 #include "arrow/type_traits.h"
 
 #include "arrow/matlab/array/proxy/array.h"
+#include "arrow/matlab/bit/bit_pack_matlab_logical_array.h"
 
 #include "libmexclass/proxy/Proxy.h"
 
 namespace arrow::matlab::array::proxy {
 
+namespace {
+const uint8_t* getUnpackedValidityBitmap(const ::matlab::data::TypedArray<bool>& valid_elements) {
+    const auto valid_elements_iterator(valid_elements.cbegin());
+    return reinterpret_cast<const uint8_t*>(valid_elements_iterator.operator->());

Review Comment:
   Unfortunately, the current design of the MATLAB Data APIs doesn't provide an easier way of extracting the raw data without making a copy. The `->operator()` syntax is the only way to achieve this at the moment.
   
   We know this isn't a great solution, and we have reached out to the relevant product teams at MathWorks to see if we can come up with a better solution for a future MATLAB release.



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