Attempt reading old-style Matlab class in v7.3 as struct (#198)

* Attempt reading old classes in v7.3 as struct

* Add test file

Author: Jeroen-van-der-Meer

src/MAT_HDF5.jl

@@ -229,7 +229,7 @@ function m_read(g::HDF5.Group)
             @warn "MATLAB $mattype values are currently not supported"
             return missing
         else
-            error("Cannot read from a non-struct group, type was $mattype")
+            @warn "Unknown non-struct group of type $mattype detected; attempting to read as struct"
         end
     end
     if haskey(g, "MATLAB_fields")

test/read.jl

@@ -230,3 +230,10 @@ let objtestfile = "struct_table_datetime.mat"
     @test "testDatetime" in keys(vars)
     @test ismissing(vars["testDatetime"])
 end
+
+# test reading of old-style Matlab object in v7.3 format
+let objtestfile = "old_class.mat"
+    vars = matread(joinpath(dirname(@__FILE__), "v7.3", objtestfile))
+    @test "tc_old" in keys(vars)
+    @test "foo" in keys(vars["tc_old"])
+end