Skip to main content

Apache OpenDAL™ D Binding

A D language binding for OpenDAL, wrapping the C binding to give D programs access to the same unified storage API as every other OpenDAL binding.

New to the model behind the API? Read Concepts first — service, operator, layer, and operation are the same four ideas in every language.

warning

This binding is early-stage and experimental. It is not yet released or published to a package registry. The API surface is minimal, the build requires building from source, and breaking changes can happen at any time.

Status​

Unreleased. Must be built from source. Suitable for experimentation and contribution, not for production use.

Capabilities​

The current API exposes a single Operator struct with the following methods:

MethodDescription
write(path, data)Write ubyte[] to path
read(path)Return ubyte[] from path
remove(path)Delete the object at path
exists(path)Return bool indicating whether path exists
stat(path)Return a Metadata struct for path
list(path)Return an Entry[] listing the directory at path
createDir(path)Create a directory at path
rename(src, dest)Rename / move src to dest
copy(src, dest)Copy src to dest

Three operations have parallel variants: writeParallel, readParallel, and listParallel. Each dispatches the call to a std.parallelism.TaskPool. Parallel variants are enabled by passing useParallel = true to the Operator constructor.

Metadata exposes contentLength(), isFile(), isDir(), and lastModified(). Entry exposes path() and name().

Most methods are @trusted wrappers around the underlying C binding. writeParallel is @safe. Entry.path() and Entry.name() carry no safety attribute (default @system) because they call into the C binding without a @trusted annotation. There is no async API at this stage.

Building from Source​

You need:

  • A D compiler: dmd, ldc, or gdc
  • Rust and Cargo (to build the underlying C library)
# From the bindings/d/ directory

# Build libopendal_c and the D library (release mode)
OPENDAL_TEST=memory dub build -b release

# Build and run unit tests against the memory backend
OPENDAL_TEST=memory dub test

The pre-build script (build.d) reads OPENDAL_TEST at build time to decide which Cargo --features (i.e. which storage backends) get compiled into the C library. The resulting static library is copied into lib/ before dub links the D code. Omitting OPENDAL_TEST builds only core functionality with no storage backends.

At runtime the test suite also reads OPENDAL_TEST to select which backend scheme to pass to Operator(...). The runtime backend is constructed with Operator(scheme, options) where options holds service-specific keys such as root.

To test against a service other than memory, set OPENDAL_TEST and the matching OPENDAL_{SERVICE}_* configuration variables:

OPENDAL_TEST=fs OPENDAL_FS_ROOT=/tmp/test dub test

Next Steps​