I just spent a couple of days on figuring out how to properly get a pointer to an array of C-structs. I finally figured it out, but it seems like more work than necessary, and I'm wondering what other folks think. I'm using Harfbuzz, a C library, to do some OpenType text shaping & positioning -- that is, converting a Unicode string, plus a given font, to a sequence of glyphs with positions. In this specific code, I'm trying to convert an array of Ruby strings to 'features,' which are represented in Harfbuzz by the 'hb_feature_t' struct. The function hb_feature_from_string() handles the conversion, but needs a pointer to a pre-allocated 'hb_feature_t' struct. The set of features needs to be stored as an array of contiguous structs, which is then passed into the shaping function hb_shape(). Here are the definitions from the .h files: typedef struct hb_feature_t { hb_tag_t tag; uint32_t value; unsigned int start; unsigned int end; } hb_feature_t; hb_feature_from_string (const char *str, int len, hb_feature_t *feature); hb_shape (hb_font_t *font, hb_buffer_t *buffer, const hb_feature_t *features, unsigned int num_features); I've built a small framework with the Harfbuzz library and the BridgeSupport file that resulted from running gen_bridge_metadata on those .h files. Here are excerpts from my current working MacRuby code. feature_strings = %w{dlig kern} features = feature_strings.map do |feature_string| feature = Pointer.new('{hb_feature_t=IIII}') hb_feature_from_string(feature_string, -1, feature) feature.value end features_ptr = Pointer.new_with_type('^{hb_feature_t=IIII}') features_ptr.assign(features) @features = features_ptr.value @num_features = features.length # ...later on... hb_shape_full(@font.hb_font, buffer, @features, @num_features) In my first attempts, I tried to allocated a single Pointer object that would contain all the features, and then call hb_feature_from_string() with each element in turn, like this: @features = Pointer.new('{hb_feature_t=IIII}', feature_strings.length) feature_strings.each_with_index do |feature_string, i| hb_feature_from_string(feature_string, -1, @features[i]) end @num_features = feature_strings.length The code ran, but the '@features' pointer remained in the initialized state -- that is, all the values were 0. I tried this in several different ways, and no matter what, the values were never set. This seems like a potential bug. (It also seems odd to need to specify the exact members of the type -- the '=IIII' part -- but MacRuby complained mightily when I removed that part.) Can some Pointer guru take a look at the above and give me a reality check? Is the way I'm doing it just the way it must be done? Or should the second method, with the single Pointer object, actually work? Best, --John