fix: preserve logical datatype (#2)

Found that variable declared as `logical` were being read back in as `uint8`. It turns out that MATLAB manages the datatype with more than one dataset attribute. This PR copies over all dataset attributes in a loop, which solves the problem.

* Tests that reading logical from MAT-file yields logical, which fails

* Copy over all dataset attributes, not just MATLAB_class...

This change preserves logical datatype on read

* Bump version

VERSION

@@ -1 +1 @@
-0.2.0
+0.2.1

newmatic.m

@@ -35,7 +35,7 @@
 out_fcpl = H5P.copy(ref_fcpl);
 out_fid = H5F.create(out_file, 'H5F_ACC_EXCL', out_fcpl, 'H5P_DEFAULT');
 
-% copy over datasets (a.k.a., variables), applying chunking as needed
+% copy datasets (a.k.a., variables), applying chunking as needed
 for ii = 1:length(varargin)
     var = varargin{ii};
 
@@ -53,18 +53,23 @@
         H5D.get_space(ref_ds_id), ...
         out_ds_cpl);
 
-    % note: assume that only this one attribute exists (cribbed from manual inspection of files
-    %   created by matfile function)
-    ref_attr_id = H5A.open(ref_ds_id, 'MATLAB_class');
+    % copy dataset attributes
+    ref_ds_info = H5O.get_info(ref_ds_id);
 
-    out_attr_id = H5A.create(...
-        out_ds_id, ...
-        'MATLAB_class', ...
-        H5A.get_type(ref_attr_id), ...
-        H5A.get_space(ref_attr_id), ...
-        'H5P_DEFAULT');
-    H5A.write(out_attr_id, 'H5ML_DEFAULT', H5A.read(ref_attr_id));
+    for ref_attr_idx = 0:ref_ds_info.num_attrs - 1
+
+        ref_attr_id = H5A.open_by_idx(...
+            ref_fid, var.name, 'H5_INDEX_NAME', 'H5_ITER_DEC', ref_attr_idx);
 
+        out_attr_id = H5A.create(...
+            out_ds_id, ...
+            H5A.get_name(ref_attr_id), ...
+            H5A.get_type(ref_attr_id), ...
+            H5A.get_space(ref_attr_id), ...
+            'H5P_DEFAULT');
+        H5A.write(out_attr_id, 'H5ML_DEFAULT', H5A.read(ref_attr_id));
+    end
+
     H5A.close(ref_attr_id);
     H5A.close(out_attr_id);
 

test_newmatic.m

@@ -134,3 +134,14 @@ function test_input_validation(testCase)
     fclose(fopen(fname, 'w'));  % create file by touching it
     assertError(testCase, @() newmatic(fname, a_var), 'newmatic:OverwriteError');
 end
+
+
+function test_preserve_logical_dtype(testCase)
+    fname = testCase.TestData.filename;
+    mat = newmatic(fname, newmatic_variable('x', 'logical', [100, 200], [50, 100]));
+    mat.x(:, :) = false(100, 200);
+
+    % data read back from file should still be logical
+    assertClass(testCase, mat.x, 'logical');
+end
+