Error handling

Error handling is achieved via a Rust-like mechanism through ResultTypes.jl. All Vulkan API functions that return a Vulkan result code are wrapped into a ResultTypes.Result, which holds either the result or a VulkanError if a non-zero status code is encountered. Note that ResultTypes.Result is distinct from Vulkan.Result which is the wrapped version of VkResult. Errors can be manually handled with the following pattern

using Vulkan

res = create_instance(["VK_LAYER_KHRONOS_validation"], [])
if iserror(res)
    err = unwrap_error(res)
    if err.code == ERROR_INCOMPATIBLE_DRIVER
        error("""
              No driver compatible with the requested API version could be found.
              Please make sure that a driver supporting Vulkan is installed, and
              that it is up to date with the requested version.
              """)
    elseif err.code == ERROR_LAYER_NOT_PRESENT
        @warn "Validation layers not available."
        create_instance([], [])
    else
        throw(err)
    end
else # get the instance
    unwrap(res)
end

Result(Instance(Ptr{Nothing} @0x000000003d7b4f50))

Note that calling unwrap directly on the result will throw any contained VulkanError if there is one. So, if you just want to throw an exception when encountering an error, you can do

unwrap(create_instance([], []))

Instance(Ptr{Nothing} @0x000000003d55bc90)

Because it may be tedious to unwrap everything by hand and explicitly set the create info structures, convenience constructors are defined for handle types so that you can just do

Instance([], [])

Instance(Ptr{Nothing} @0x000000003d567890)

However, note that exceptions are thrown whenever the result is an error with this shorter approach.

Furthermore, all functions that may return non-success (but non-error) codes return a Vulkan.Result type along with any other returned value, since the return code may still be of interest.

For more details on the ResultTypes.Result type and how to handle it, please consult the ResultTypes.jl documentation.

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