diff --git a/fwd.hpp b/fwd.hpp
index 94a5e55..0e37d35 100644
--- a/fwd.hpp
+++ b/fwd.hpp
@@ -102,7 +102,115 @@ namespace cruft::vk {
         VK_DESCENDANT_TYPE_MAP(FUNC) \
         VK_OWNED_TYPE_MAP(FUNC)
 
-    #define VK_NATIVE_TYPE_MAP(FUNC) \
+    #define VK_NATIVE_ENUM_MAP(FUNC) \
+        MAP0(FUNC, \
+            VkImageAspectFlagBits, \
+            VkShaderStageFlagBits, \
+            VkSystemAllocationScope, \
+            VkInternalAllocationType, \
+            VkQueueFlagBits, \
+            VkStructureType, \
+            VkFilter, \
+            VkSamplerMipmapMode, \
+            VkSamplerAddressMode, \
+            VkCompareOp, \
+            VkBorderColor, \
+            VkIndexType, \
+            VkBufferCreateFlagBits, \
+            VkBufferUsageFlagBits, \
+            VkExternalMemoryHandleTypeFlagBitsKHR, \
+            VkPrimitiveTopology, \
+            VkIndirectCommandsTokenTypeNVX, \
+            VkDisplayPlaneAlphaFlagBitsKHR, \
+            VkSurfaceTransformFlagBitsKHR, \
+            VkCompositeAlphaFlagBitsKHR, \
+            VkImageUsageFlagBits, \
+            VkViewportCoordinateSwizzleNV, \
+            VkPipelineBindPoint, \
+            VkExternalMemoryFeatureFlagBitsNV, \
+            VkDebugReportFlagBitsEXT, \
+            VkDebugReportObjectTypeEXT, \
+            VkCommandBufferResetFlagBits, \
+            VkPhysicalDeviceType, \
+            VkFenceImportFlagBitsKHR, \
+            VkExternalFenceHandleTypeFlagBitsKHR, \
+            VkQueryType, \
+            VkQueryPipelineStatisticFlagBits, \
+            VkExternalSemaphoreHandleTypeFlagBitsKHR, \
+            VkImageLayout, \
+            VkFormatFeatureFlagBits, \
+            VkObjectEntryTypeNVX, \
+            VkObjectEntryUsageFlagBitsNVX, \
+            VkDescriptorType, \
+            VkSparseImageFormatFlagBits, \
+            VkComponentSwizzle, \
+            VkDescriptorSetLayoutCreateFlagBits, \
+            VkIndirectCommandsLayoutUsageFlagBitsNVX, \
+            VkAttachmentDescriptionFlagBits, \
+            VkSampleCountFlagBits, \
+            VkAttachmentLoadOp, \
+            VkAttachmentStoreOp, \
+            VkImageType, \
+            VkImageTiling, \
+            VkExternalMemoryFeatureFlagBitsKHR, \
+            VkStencilFaceFlagBits, \
+            VkStencilOp, \
+            VkPolygonMode, \
+            VkCullModeFlagBits, \
+            VkFrontFace, \
+            VkImageCreateFlagBits, \
+            VkExternalMemoryHandleTypeFlagBitsNV, \
+            VkImageViewType, \
+            VkSharingMode, \
+            VkDynamicState, \
+            VkCommandPoolCreateFlagBits, \
+            VkSemaphoreImportFlagBitsKHR, \
+            VkPipelineStageFlagBits, \
+            VkSwapchainCreateFlagBitsKHR, \
+            VkMemoryHeapFlagBits, \
+            VkPipelineCreateFlagBits, \
+            VkBlendOverlapEXT, \
+            VkSurfaceCounterFlagBitsEXT, \
+            VkDescriptorUpdateTemplateTypeKHR, \
+            VkExternalFenceFeatureFlagBitsKHR, \
+            VkQueryResultFlagBits, \
+            VkSparseMemoryBindFlagBits, \
+            VkValidationCacheHeaderVersionEXT, \
+            VkDeviceGroupPresentModeFlagBitsKHX, \
+            VkColorSpaceKHR, \
+            VkPresentModeKHR, \
+            VkCommandPoolResetFlagBits, \
+            VkVertexInputRate, \
+            VkSubpassDescriptionFlagBits, \
+            VkAccessFlagBits, \
+            VkDependencyFlagBits, \
+            VkExternalSemaphoreFeatureFlagBitsKHR, \
+            VkBlendFactor, \
+            VkBlendOp, \
+            VkColorComponentFlagBits, \
+            VkMemoryPropertyFlagBits, \
+            VkCommandBufferUsageFlagBits, \
+            VkQueryControlFlagBits, \
+            VkCommandBufferLevel, \
+            VkValidationCheckEXT, \
+            VkSubpassContents, \
+            VkLogicOp, \
+            VkDisplayPowerStateEXT, \
+            VkFenceCreateFlagBits, \
+            VkDisplayEventTypeEXT, \
+            VkDescriptorPoolCreateFlagBits, \
+            VkPeerMemoryFeatureFlagBitsKHX, \
+            VkCoverageModulationModeNV, \
+            VkObjectType, \
+            VkMemoryAllocateFlagBitsKHX, \
+            VkPipelineCacheHeaderVersion, \
+            VkDiscardRectangleModeEXT, \
+            VkDeviceEventTypeEXT, \
+            VkSamplerReductionModeEXT, \
+            VkRasterizationOrderAMD \
+        )
+
+    #define VK_NATIVE_STRUCT_MAP(FUNC) \
         MAP0(FUNC, \
              VkClearColorValue, \
              VkClearValue, \
@@ -379,6 +487,10 @@ namespace cruft::vk {
              VkValidationCacheCreateInfoEXT, \
              VkShaderModuleValidationCacheCreateInfoEXT)
 
+    #define VK_NATIVE_TYPE_MAP(FUNC) \
+        VK_NATIVE_ENUM_MAP(FUNC) \
+        VK_NATIVE_STRUCT_MAP(FUNC)
+
 }
 
 #endif
diff --git a/object.hpp b/object.hpp
index 07e948b..6f941ac 100644
--- a/object.hpp
+++ b/object.hpp
@@ -190,6 +190,10 @@ namespace cruft::vk {
         SelfT& operator* ()& noexcept
         { return m_self; }
 
+        const SelfT*
+        operator-> () const& noexcept
+        { return &m_self; }
+
         SelfT*
         operator-> ()& noexcept
         { return &m_self; }
@@ -229,6 +233,65 @@ namespace cruft::vk {
             owner
         };
     };
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename ReturnT, typename ...Args>
+    struct function_wrapper {
+        using value_type = ReturnT(*)(Args...) noexcept;
+
+        constexpr function_wrapper (value_type _value): m_function {_value} { ; }
+        constexpr function_wrapper (): m_function { nullptr } { ; }
+
+
+        value_type
+        reset (value_type _value)
+        {
+            value_type old = std::move (m_function);
+            m_function = _value;
+            return old;
+        }
+
+
+        template <typename SelfT, typename ...Tail>
+        auto
+        operator () (const owned_ptr<SelfT> &owned, Tail &&...tail) const
+        {
+            return dispatch (owned.owner (), owned.get (), std::forward<Tail> (tail)...);
+        }
+
+
+        template <typename ...Tail>
+        auto operator () (Tail &&...tail) const
+        {
+            return dispatch (std::forward<Tail> (tail)...);
+        }
+
+
+    private:
+        template <typename ...Tail>
+        auto dispatch (Tail &&...tail) const
+        {
+            if constexpr (is_values_function_v<value_type>)
+                return error::try_values (m_function, std::forward<Tail> (tail)...);
+            else if constexpr (is_query_function_v<value_type>)
+                return error::try_query (m_function, std::forward<Tail> (tail)...);
+            else
+                return error::try_func (m_function, std::forward<Tail> (tail)...);
+        }
+
+
+        value_type m_function;
+    };
+
+
+    #define WRAP_FUNCTION(NAME,FUNC)                                \
+    namespace detail { const function_wrapper __##NAME {FUNC}; }    \
+    template <typename ...Args>                                     \
+    auto NAME (Args &&...args)                                      \
+    {                                                               \
+        return detail::__##NAME (std::forward<Args> (args)... );    \
+    };
 };
 
 #endif
diff --git a/physical_device.cpp b/physical_device.cpp
index 9513928..eb951f4 100644
--- a/physical_device.cpp
+++ b/physical_device.cpp
@@ -58,16 +58,6 @@ physical_device::features (void) const
 }
 
 
-//-----------------------------------------------------------------------------
-VkSurfaceCapabilitiesKHR
-physical_device::surface_capabilities (surface &_surface) const
-{
-    return error::try_query (
-        vkGetPhysicalDeviceSurfaceCapabilitiesKHR, native (), _surface
-    );
-}
-
-
 //-----------------------------------------------------------------------------
 VkPhysicalDeviceMemoryProperties
 physical_device::memory_properties (void) const
@@ -88,28 +78,6 @@ physical_device::queue_families (void) const
 }
 
 
-///////////////////////////////////////////////////////////////////////////////
-std::vector<VkSurfaceFormatKHR>
-physical_device::surface_formats (surface &_surface)
-{
-    return error::try_values (
-        vkGetPhysicalDeviceSurfaceFormatsKHR,
-        native (), _surface
-    );
-}
-
-
-//-----------------------------------------------------------------------------
-std::vector<VkPresentModeKHR>
-physical_device::present_modes (surface &_surface)
-{
-    return error::try_values (
-        vkGetPhysicalDeviceSurfacePresentModesKHR,
-        native (), _surface
-    );
-}
-
-
 ///////////////////////////////////////////////////////////////////////////////
 std::string
 physical_device::name (void) const
diff --git a/physical_device.hpp b/physical_device.hpp
index b9b90ce..8855f77 100644
--- a/physical_device.hpp
+++ b/physical_device.hpp
@@ -33,14 +33,10 @@ namespace cruft::vk {
 
         VkPhysicalDeviceProperties properties (void) const;
         VkPhysicalDeviceFeatures features (void) const;
-        VkSurfaceCapabilitiesKHR surface_capabilities (surface&) const;
         VkPhysicalDeviceMemoryProperties memory_properties (void) const;
 
         std::vector<VkQueueFamilyProperties> queue_families (void) const;
 
-        std::vector<VkSurfaceFormatKHR> surface_formats (surface&);
-        std::vector<VkPresentModeKHR> present_modes (surface&);
-
         std::string name (void) const;
     };
 }
diff --git a/surface.cpp b/surface.cpp
index 4851431..030ac53 100644
--- a/surface.cpp
+++ b/surface.cpp
@@ -18,6 +18,6 @@
 #include "./surface.hpp"
 
 #include "./instance.hpp"
+#include "./physical_device.hpp"
 
 using cruft::vk::surface;
-
diff --git a/surface.hpp b/surface.hpp
index 6419ae0..d5b7d7e 100644
--- a/surface.hpp
+++ b/surface.hpp
@@ -24,9 +24,16 @@
 
 
 namespace cruft::vk {
+    ///////////////////////////////////////////////////////////////////////////
     struct surface : public owned<surface,instance> {
         using owned::owned;
     };
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    WRAP_FUNCTION (capabilities,  vkGetPhysicalDeviceSurfaceCapabilitiesKHR);
+    WRAP_FUNCTION (formats,       vkGetPhysicalDeviceSurfaceFormatsKHR);
+    WRAP_FUNCTION (present_modes, vkGetPhysicalDeviceSurfacePresentModesKHR);
 };
 
 #endif
diff --git a/swapchain.hpp b/swapchain.hpp
index 8d78611..f679171 100644
--- a/swapchain.hpp
+++ b/swapchain.hpp
@@ -24,6 +24,9 @@ namespace cruft::vk {
     struct swapchain : public owned<swapchain,device> {
         using owned::owned;
     };
+
+
+    function_wrapper<decltype(&vkGetSwapchainImagesKHR)> images;
 };
 
 #endif
diff --git a/tools/hello.cpp b/tools/hello.cpp
index 7b0eec8..d52f550 100644
--- a/tools/hello.cpp
+++ b/tools/hello.cpp
@@ -19,11 +19,14 @@
 #include <GLFW/glfw3.h>
 #include <GLFW/glfw3native.h>
 
+#include <cruft/util/extent.hpp>
 #include <cruft/util/io.hpp>
 #include <cruft/util/log.hpp>
 #include <cruft/util/colour.hpp>
 #include <cruft/util/point.hpp>
 
+#include <atomic>
+#include <mutex>
 #include <iostream>
 #include <experimental/filesystem>
 
@@ -69,27 +72,237 @@ static constexpr vertex_t VERTICES[] = {
 };
 
 
+namespace glfw {
+    namespace detail {
+        constexpr const char* error_string (int code) noexcept;
+    }
+
+
+    struct error : public std::exception {
+    public:
+        static void try_code (int code);
+        static void throw_code [[noreturn]] (int code);
+        static void throw_code [[noreturn]] (void);
+
+        static void push (int code)
+        {
+            s_current = code;
+        }
+
+    private:
+        static std::atomic<int> s_current;
+    };
+
+
+    template <int CodeV>
+    struct error_code : public error {
+        virtual ~error_code () = default;
+        static constexpr const char *message = detail::error_string (CodeV);
+    };
+}
+
+
+std::atomic<int> glfw::error::s_current;
+
+
+void
+glfw_error_callback (int code ,const char *description)
+{
+    LOG_WARN ("glfw: %s", description);
+    glfw::error::push (code);
+}
+
+
+namespace glfw {
+    class instance {
+    public:
+        instance ()
+        {
+            if (std::lock_guard l {s_count.guard}; !s_count.value++)
+                glfwInit ();
+
+            glfwSetErrorCallback (glfw_error_callback);
+
+            static constexpr struct {
+                int tag;
+                int val;
+            } HINTS[] {
+                { GLFW_CLIENT_API, GLFW_NO_API },
+                { GLFW_RESIZABLE,  GLFW_FALSE  },
+            };
+
+            for (const auto [tag,val]: HINTS)
+                glfwWindowHint (tag, val);
+        }
+
+
+        std::vector<const char*>
+        required_extensions (void) const
+        {
+            unsigned count;
+            auto values = glfwGetRequiredInstanceExtensions (&count);
+
+            return {
+                values + 0,
+                values + count
+            };
+        }
+
+
+        void poll_events (void)
+        {
+            glfwPollEvents ();
+        }
+
+        ~instance ()
+        {
+            if (std::lock_guard l {s_count.guard}; !--s_count.value)
+                glfwTerminate ();
+        }
+
+
+    private:
+        // TODO: value doesnt' need to be atomic, but it's not performance
+        // critical, and I'm not particularly familiar with c++ memory
+        // ordering primitives. so it's probably safer this way for now.
+        static struct count_t {
+            std::mutex guard;
+            std::atomic<int> value;
+        } s_count;
+    };
+
+
+    class window {
+    public:
+        using native_t = GLFWwindow*;
+
+        window (util::extent2i resolution, const char *name):
+            m_native (glfwCreateWindow (resolution.w, resolution.h, name, nullptr, nullptr))
+        {
+            if (!m_native)
+                error::throw_code ();
+        }
+
+        native_t native (void) const { return m_native; }
+
+        bool
+        should_close (void) const
+        {
+            return glfwWindowShouldClose (native ());
+        }
+
+
+    private:
+        native_t m_native;
+    };
+};
+
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <typename T>
+struct to_format;
+
+
+#define TO_FORMAT(S,T,VALUE)                        \
+template <template <size_t,typename> class KlassT>  \
+struct to_format<KlassT<S,T>> {                     \
+    static constexpr auto value = VkFormat::VALUE;  \
+};
+
+
+TO_FORMAT(1,float,VK_FORMAT_R32_SFLOAT);
+TO_FORMAT(2,float,VK_FORMAT_R32G32_SFLOAT);
+TO_FORMAT(3,float,VK_FORMAT_R32G32B32_SFLOAT);
+TO_FORMAT(4,float,VK_FORMAT_R32G32B32A32_SFLOAT);
+
+
+template <typename T>
+constexpr auto to_format_v = to_format<T>::value;
+
+
+///////////////////////////////////////////////////////////////////////////////
+struct glfw::instance::count_t glfw::instance::s_count;
+
+
+///////////////////////////////////////////////////////////////////////////////
+constexpr const char*
+glfw::detail::error_string (int code) noexcept
+{
+    switch (code) {
+        case GLFW_NOT_INITIALIZED:      return "Not initialised";
+        case GLFW_NO_CURRENT_CONTEXT:   return "No current context";
+        case GLFW_INVALID_ENUM:         return "Invalid enum";
+        case GLFW_INVALID_VALUE:        return "Invalid value";
+        case GLFW_OUT_OF_MEMORY:        return "Out of memory";
+        case GLFW_API_UNAVAILABLE:      return "API unavailable";
+        case GLFW_VERSION_UNAVAILABLE:  return "Version unavailable";
+        case GLFW_PLATFORM_ERROR:       return "Platform error";
+        case GLFW_FORMAT_UNAVAILABLE:   return "Format unavailable";
+        case GLFW_NO_WINDOW_CONTEXT:    return "No window context";
+    }
+
+    unhandled (code);
+}
+
+
+//-----------------------------------------------------------------------------
+void
+glfw::error::try_code (int code)
+{
+    if (__builtin_expect (code, 0))
+        throw_code (code);
+}
+
+
+//-----------------------------------------------------------------------------
+void
+glfw::error::throw_code [[noreturn]] (int code)
+{
+    switch (code) {
+        case GLFW_NOT_INITIALIZED:      throw error_code<GLFW_NOT_INITIALIZED> {};
+        case GLFW_NO_CURRENT_CONTEXT:   throw error_code<GLFW_NO_CURRENT_CONTEXT> {};
+        case GLFW_INVALID_ENUM:         throw error_code<GLFW_INVALID_ENUM> {};
+        case GLFW_INVALID_VALUE:        throw error_code<GLFW_INVALID_VALUE> {};
+        case GLFW_OUT_OF_MEMORY:        throw error_code<GLFW_OUT_OF_MEMORY> {};
+        case GLFW_API_UNAVAILABLE:      throw error_code<GLFW_API_UNAVAILABLE> {};
+        case GLFW_VERSION_UNAVAILABLE:  throw error_code<GLFW_VERSION_UNAVAILABLE> {};
+        case GLFW_PLATFORM_ERROR:       throw error_code<GLFW_PLATFORM_ERROR> {};
+        case GLFW_FORMAT_UNAVAILABLE:   throw error_code<GLFW_FORMAT_UNAVAILABLE> {};
+        case GLFW_NO_WINDOW_CONTEXT:    throw error_code<GLFW_NO_WINDOW_CONTEXT> {};
+    }
+
+    unhandled (code);
+}
+
+
+//-----------------------------------------------------------------------------
+void
+glfw::error::throw_code [[noreturn]] (void)
+{
+    throw_code (s_current);
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+class system {
+public:
+    system ();
+};
+
+
 ///////////////////////////////////////////////////////////////////////////////
 int
 main (void)
 {
     LOG_INFO ("intialising glfw");
-    glfwInit ();
+    glfw::instance glfw_instance;
 
-    LOG_INFO ("intialising window");
-    glfwWindowHint (GLFW_CLIENT_API, GLFW_NO_API);
-    glfwWindowHint (GLFW_RESIZABLE, GLFW_FALSE);
+    util::extent2i resolution { 800, 600 };
+    glfw::window window (resolution, "vkcruft-hello");
 
-    int resolution_x = 800, resolution_y = 600;
-    auto window = glfwCreateWindow (resolution_x, resolution_y, "vkcruft-hello", nullptr, nullptr);
-    if (!window) {
-        LOG_ERROR("unable to initialised GLFW");
-        return -1;
-    }
 
-    unsigned int glfwExtensionCount;
-    auto glfwExtensions = glfwGetRequiredInstanceExtensions (&glfwExtensionCount);
-    std::vector<const char*> extensions (glfwExtensions + 0, glfwExtensions + glfwExtensionCount);
+    auto extensions = glfw_instance.required_extensions ();
     extensions.push_back ("VK_EXT_debug_report");
 
     const char* layers[] = {
@@ -130,14 +343,14 @@ main (void)
     //-------------------------------------------------------------------------
     auto surface = cruft::vk::make_owned<cruft::vk::surface> (
         cruft::vk::error::try_query (
-            glfwCreateWindowSurface, instance.native (), window, nullptr
+            glfwCreateWindowSurface, instance.native (), window.native (), nullptr
         ),
         instance
     );
 
-    auto surface_capabilities = pdevice.surface_capabilities (surface.get ());
-    auto surface_formats = pdevice.surface_formats (surface.get ());
-    auto present_modes = pdevice.present_modes (surface.get ());
+    auto surface_capabilities = capabilities (pdevice, surface);
+    auto surface_formats = formats (pdevice, surface);
+    auto surface_modes = present_modes (pdevice, surface);
 
     auto queues = pdevice.queue_families ();
     int graphics_queue_id = -1, present_queue_id = -1;
@@ -212,12 +425,12 @@ main (void)
     VkPresentModeKHR present_mode = VK_PRESENT_MODE_FIFO_KHR;
     VkExtent2D present_extent {
         .width = util::limit (
-            unsigned (resolution_x),
+            unsigned (resolution.w),
             surface_capabilities.minImageExtent.width,
             surface_capabilities.maxImageExtent.width
         ),
         .height = util::limit (
-            unsigned (resolution_y),
+            unsigned (resolution.h),
             surface_capabilities.minImageExtent.height,
             surface_capabilities.maxImageExtent.height
         )
@@ -285,9 +498,13 @@ main (void)
     auto graphics_queue = cruft::vk::make_owned<cruft::vk::queue> (ldevice, graphics_queue_id, 0);
     auto present_queue = cruft::vk::make_owned<cruft::vk::queue> (ldevice, present_queue_id, 0);
 
+
+    //-------------------------------------------------------------------------
     auto vert_module = cruft::vk::make_owned<cruft::vk::shader_module> (ldevice, "./hello.vert.spv");
     auto frag_module = cruft::vk::make_owned<cruft::vk::shader_module> (ldevice, "./hello.frag.spv");
 
+
+    //-------------------------------------------------------------------------
     VkBufferCreateInfo buffer_info {};
     buffer_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
     buffer_info.size = sizeof (VERTICES);
@@ -328,6 +545,7 @@ main (void)
         memcpy (std::data (data), std::data (VERTICES), sizeof (VERTICES));
     }
 
+    //-------------------------------------------------------------------------
     VkPipelineShaderStageCreateInfo vert_stage_info {};
     vert_stage_info.sType = cruft::vk::structure_type_v<VkPipelineShaderStageCreateInfo>;
     vert_stage_info.stage = VK_SHADER_STAGE_VERTEX_BIT;
@@ -342,6 +560,8 @@ main (void)
         vert_stage_info, frag_stage_info
     };
 
+
+    //-------------------------------------------------------------------------
     VkVertexInputBindingDescription vertex_binding {};
     vertex_binding.binding = 0;
     vertex_binding.stride = sizeof (vertex_t);
@@ -350,14 +570,16 @@ main (void)
     std::array<VkVertexInputAttributeDescription,2> vertex_attribute {};
     vertex_attribute[0].binding = 0;
     vertex_attribute[0].location = 0;
-    vertex_attribute[0].format = VK_FORMAT_R32G32_SFLOAT;
+    vertex_attribute[0].format = to_format_v<decltype(VERTICES[0].position)>;
     vertex_attribute[0].offset = offsetof(vertex_t, position);
 
     vertex_attribute[1].binding = 0;
     vertex_attribute[1].location = 1;
-    vertex_attribute[1].format = VK_FORMAT_R32G32B32_SFLOAT;
+    vertex_attribute[1].format = to_format_v<decltype(VERTICES[0].colour)>;
     vertex_attribute[1].offset = offsetof (vertex_t, colour);
 
+
+    //-------------------------------------------------------------------------
     VkPipelineVertexInputStateCreateInfo vertex_input {};
     vertex_input.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
     vertex_input.vertexBindingDescriptionCount = 1;
@@ -370,10 +592,12 @@ main (void)
     assembly_info.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
     assembly_info.primitiveRestartEnable = VK_FALSE;
 
+
+    //-------------------------------------------------------------------------
     VkViewport viewport {
         .x = 0.f,
         .y = 0.f,
-        .width = float (present_extent.width),
+        .width  = float (present_extent.width),
         .height = float (present_extent.height),
         .minDepth = 0.f,
         .maxDepth = 1.f,
@@ -384,6 +608,53 @@ main (void)
         .extent = present_extent
     };
 
+
+    //-------------------------------------------------------------------------
+    VkPipelineLayoutCreateInfo pipeline_layout_info {};
+    pipeline_layout_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
+    pipeline_layout_info.setLayoutCount = 0;
+    pipeline_layout_info.pSetLayouts = nullptr;
+    pipeline_layout_info.pushConstantRangeCount = 0;
+    pipeline_layout_info.pPushConstantRanges = 0;
+
+    auto pipeline_layout = cruft::vk::make_owned<cruft::vk::pipeline_layout> (
+        ldevice, &pipeline_layout_info, nullptr
+    );
+
+
+    //-------------------------------------------------------------------------
+    VkAttachmentDescription color_attachment {};
+    color_attachment.format         = surface_format.format;
+    color_attachment.samples        = VK_SAMPLE_COUNT_1_BIT;
+    color_attachment.loadOp         = VK_ATTACHMENT_LOAD_OP_CLEAR;
+    color_attachment.storeOp        = VK_ATTACHMENT_STORE_OP_STORE;
+    color_attachment.stencilLoadOp  = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+    color_attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+    color_attachment.initialLayout  = VK_IMAGE_LAYOUT_UNDEFINED;
+    color_attachment.finalLayout    = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+
+    VkAttachmentReference colour_attachment_ref {};
+    colour_attachment_ref.attachment = 0;
+    colour_attachment_ref.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+
+    VkSubpassDescription subpass {};
+    subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+    subpass.colorAttachmentCount = 1;
+    subpass.pColorAttachments = &colour_attachment_ref;
+
+    VkRenderPassCreateInfo render_pass_info {};
+    render_pass_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
+    render_pass_info.attachmentCount = 1;
+    render_pass_info.pAttachments = &color_attachment;
+    render_pass_info.subpassCount = 1;
+    render_pass_info.pSubpasses = &subpass;
+
+    auto render_pass = cruft::vk::make_owned<cruft::vk::render_pass> (
+        ldevice, &render_pass_info, nullptr
+    );
+
+
+    //-------------------------------------------------------------------------
     VkPipelineViewportStateCreateInfo viewport_create_info {};
     viewport_create_info.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
     viewport_create_info.viewportCount = 1;
@@ -414,66 +685,29 @@ main (void)
     multisampling.alphaToOneEnable = VK_FALSE;
 
     VkPipelineColorBlendAttachmentState blend_attachment = {};
-    blend_attachment.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+    blend_attachment.colorWriteMask =
+        VK_COLOR_COMPONENT_R_BIT |
+        VK_COLOR_COMPONENT_G_BIT |
+        VK_COLOR_COMPONENT_B_BIT |
+        VK_COLOR_COMPONENT_A_BIT;
     blend_attachment.blendEnable = VK_FALSE;
-    blend_attachment.srcColorBlendFactor = VK_BLEND_FACTOR_ONE; // Optional
-    blend_attachment.dstColorBlendFactor = VK_BLEND_FACTOR_ZERO; // Optional
-    blend_attachment.colorBlendOp = VK_BLEND_OP_ADD; // Optional
-    blend_attachment.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE; // Optional
-    blend_attachment.dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO; // Optional
-    blend_attachment.alphaBlendOp = VK_BLEND_OP_ADD; // Optional
+    blend_attachment.srcColorBlendFactor = VK_BLEND_FACTOR_ONE;
+    blend_attachment.dstColorBlendFactor = VK_BLEND_FACTOR_ZERO;
+    blend_attachment.colorBlendOp        = VK_BLEND_OP_ADD;
+    blend_attachment.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE;
+    blend_attachment.dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO;
+    blend_attachment.alphaBlendOp        = VK_BLEND_OP_ADD;
 
     VkPipelineColorBlendStateCreateInfo colour_blend = {};
     colour_blend.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
     colour_blend.logicOpEnable = VK_FALSE;
-    colour_blend.logicOp = VK_LOGIC_OP_COPY; // Optional
+    colour_blend.logicOp = VK_LOGIC_OP_COPY;
     colour_blend.attachmentCount = 1;
     colour_blend.pAttachments = &blend_attachment;
-    colour_blend.blendConstants[0] = 0.0f; // Optional
-    colour_blend.blendConstants[1] = 0.0f; // Optional
-    colour_blend.blendConstants[2] = 0.0f; // Optional
-    colour_blend.blendConstants[3] = 0.0f; // Optional
-
-    VkPipelineLayoutCreateInfo pipeline_layout_info {};
-    pipeline_layout_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
-    pipeline_layout_info.setLayoutCount = 0; // Optional
-    pipeline_layout_info.pSetLayouts = nullptr; // Optional
-    pipeline_layout_info.pushConstantRangeCount = 0; // Optional
-    pipeline_layout_info.pPushConstantRanges = 0; // Optional
-
-    auto pipeline_layout = cruft::vk::make_owned<cruft::vk::pipeline_layout> (
-        ldevice, &pipeline_layout_info, nullptr
-    );
-
-    VkAttachmentDescription color_attachment {};
-    color_attachment.format = surface_format.format;
-    color_attachment.samples = VK_SAMPLE_COUNT_1_BIT;
-    color_attachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
-    color_attachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
-    color_attachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
-    color_attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
-    color_attachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
-    color_attachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
-
-    VkAttachmentReference colour_attachment_ref {};
-    colour_attachment_ref.attachment = 0;
-    colour_attachment_ref.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
-
-    VkSubpassDescription subpass {};
-    subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
-    subpass.colorAttachmentCount = 1;
-    subpass.pColorAttachments = &colour_attachment_ref;
-
-    VkRenderPassCreateInfo render_pass_info {};
-    render_pass_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
-    render_pass_info.attachmentCount = 1;
-    render_pass_info.pAttachments = &color_attachment;
-    render_pass_info.subpassCount = 1;
-    render_pass_info.pSubpasses = &subpass;
-
-    auto render_pass = cruft::vk::make_owned<cruft::vk::render_pass> (
-        ldevice, &render_pass_info, nullptr
-    );
+    colour_blend.blendConstants[0] = 0.0f;
+    colour_blend.blendConstants[1] = 0.0f;
+    colour_blend.blendConstants[2] = 0.0f;
+    colour_blend.blendConstants[3] = 0.0f;
 
     VkGraphicsPipelineCreateInfo pipeline_info {};
     pipeline_info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
@@ -492,17 +726,23 @@ main (void)
     pipeline_info.basePipelineHandle = VK_NULL_HANDLE;
     pipeline_info.basePipelineIndex = -1;
 
-    auto graphics_pipeline = cruft::vk::make_owned<cruft::vk::pipeline<cruft::vk::bindpoint::GRAPHICS>> (
+    auto graphics_pipeline = cruft::vk::make_owned<
+        cruft::vk::pipeline<cruft::vk::bindpoint::GRAPHICS>
+    > (
         ldevice, VK_NULL_HANDLE, 1, &pipeline_info, nullptr
     );
 
+
+    //-------------------------------------------------------------------------
     using framebuffer_ptr = cruft::vk::owned_ptr<cruft::vk::framebuffer>;
     std::vector<framebuffer_ptr> swapchain_framebuffers;
-    swapchain_framebuffers.reserve (swap_image_views.size ());
 
-    for (size_t i = 0; i < swap_image_views.size (); ++i) {
+    std::transform (std::cbegin (swap_image_views),
+                    std::cend   (swap_image_views),
+                    std::back_inserter (swapchain_framebuffers),
+                    [&] (const auto &i) {
         VkImageView attachments[] = {
-            swap_image_views[i]->native ()
+            i->native ()
         };
 
         VkFramebufferCreateInfo framebuffer_info {};
@@ -514,11 +754,11 @@ main (void)
         framebuffer_info.height = present_extent.height;
         framebuffer_info.layers = 1;
 
-        swapchain_framebuffers.push_back (
-            cruft::vk::make_owned<cruft::vk::framebuffer> (ldevice, &framebuffer_info, nullptr)
-        );
-    };
+        return cruft::vk::make_owned<cruft::vk::framebuffer> (ldevice, &framebuffer_info, nullptr);
+    });
 
+
+    //-------------------------------------------------------------------------
     VkCommandPoolCreateInfo pool_info {};
     pool_info.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
     pool_info.queueFamilyIndex = device_queues[0].queueFamilyIndex;
@@ -576,8 +816,13 @@ main (void)
     VkSemaphoreCreateInfo semaphore_info {};
     semaphore_info.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
 
-    auto image_semaphore = cruft::vk::make_owned<cruft::vk::semaphore> (ldevice, &semaphore_info, nullptr);
-    auto render_semaphore = cruft::vk::make_owned<cruft::vk::semaphore> (ldevice, &semaphore_info, nullptr);
+    auto image_semaphore  = cruft::vk::make_owned<cruft::vk::semaphore> (
+        ldevice, &semaphore_info, nullptr
+    );
+
+    auto render_semaphore = cruft::vk::make_owned<cruft::vk::semaphore> (
+        ldevice, &semaphore_info, nullptr
+    );
 
     uint32_t image_index;
     cruft::vk::error::try_code (
@@ -630,13 +875,11 @@ main (void)
     cruft::vk::error::try_func (vkQueuePresentKHR, present_queue, &present_info);
 
     LOG_INFO ("entering runloop");
-    while (!glfwWindowShouldClose (window)) {
-        glfwPollEvents ();
+    while (!window.should_close ()) {
+        glfw_instance.poll_events ();
     }
 
     cruft::vk::error::try_func (vkDeviceWaitIdle, ldevice.native ());
 
-    LOG_INFO ("terminating glfw");
-    glfwDestroyWindow (window);
-    glfwTerminate ();
+    LOG_INFO ("terminating");
 }
\ No newline at end of file
diff --git a/traits.hpp b/traits.hpp
index 0ebbb3e..ce44e44 100644
--- a/traits.hpp
+++ b/traits.hpp
@@ -124,6 +124,131 @@ namespace cruft::vk {
     static constexpr auto is_wrapper_v = is_wrapper<T>::value;
 
 
+    ///////////////////////////////////////////////////////////////////////////
+    /// determines whether a function conceptually returns a singular Vulkan
+    /// data structure.
+    ///
+    /// that is: is the last parameter a pointer to a Vulkan data type?
+    ///
+    /// a result of true probably implies the function type can be passed to
+    /// error::try_query
+    template <typename FunctionT>
+    struct is_query_function : public std::false_type {};
+
+
+    //-------------------------------------------------------------------------
+    namespace detail {
+        template <typename ...Args>
+        struct is_query_args : public std::conditional_t<
+            std::is_pointer_v<
+                std::tuple_element_t<
+                    sizeof...(Args) - 1,
+                    std::tuple<Args...>
+                >
+            > && is_native_v<
+                std::remove_pointer_t<
+                    std::tuple_element_t<
+                        sizeof...(Args) - 1,
+                        std::tuple<Args...>
+                    >
+                >
+            >,
+            std::true_type,
+            std::false_type
+        > { };
+    }
+
+
+    //-------------------------------------------------------------------------
+    template <typename ReturnT, typename ...Args>
+    struct is_query_function<
+        ReturnT(Args...)noexcept
+    > : detail::is_query_args<Args...> { };
+
+
+    template <typename ReturnT, typename ...Args>
+    struct is_query_function<
+        ReturnT(*)(Args...)noexcept
+    > : detail::is_query_args<Args...> { };
+
+
+    template <typename ReturnT, typename ...Args>
+    struct is_query_function<
+        ReturnT(&)(Args...)noexcept
+    > : detail::is_query_args<Args...> { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename FunctionT>
+    constexpr auto is_query_function_v = is_query_function<FunctionT>::value;
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// determines whether a function conceptually returns an array of values.
+    ///
+    /// that is: does it take/return uint32_t and Vulkan types as the last two
+    /// pointer parameters.
+    ///
+    /// a result of true likely implies such a function pointer can be passed
+    /// to error::try_values
+    template <typename FunctionT>
+    struct is_values_function : public std::false_type {};
+
+
+    //-------------------------------------------------------------------------
+    namespace detail {
+        template <typename ...Args>
+        struct is_values_args : public std::conditional_t<
+            std::is_same_v<
+                uint32_t*,
+                std::tuple_element_t<
+                    sizeof...(Args) - 2,
+                    std::tuple<Args...>
+                >
+            > && std::is_pointer_v<
+                std::tuple_element_t<
+                    sizeof...(Args) - 1,
+                    std::tuple<Args...>
+                >
+            > && is_native_v<
+                std::remove_pointer_t<
+                    std::tuple_element_t<
+                        sizeof...(Args) - 1,
+                        std::tuple<Args...>
+                    >
+                >
+            >,
+            std::true_type,
+            std::false_type
+        > { };
+    };
+
+    //-------------------------------------------------------------------------
+    template <typename ReturnT, typename ...Args>
+    struct is_values_function<
+        ReturnT(Args...) noexcept
+    > : detail::is_values_args<Args...> { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename ReturnT, typename ...Args>
+    struct is_values_function<
+        ReturnT(&)(Args...) noexcept
+    > : detail::is_values_args<Args...> { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename ReturnT, typename ...Args>
+    struct is_values_function<
+        ReturnT(*)(Args...) noexcept
+    > : detail::is_values_args<Args...> { };
+
+
+    //-------------------------------------------------------------------------
+    template <typename FunctionT>
+    constexpr auto is_values_function_v = is_values_function<FunctionT>::value;
+
+
     ///////////////////////////////////////////////////////////////////////////
     /// return the native value for the wrapper object
     template <typename SelfT>