API Reference — `dna/Writer`

`Reader`

A forward-declared reader type that Writer::setFrom accepts as the source when copying an entire DNA document into a writer.

Why this exists

Writer::setFrom needs to call every getter on a Reader and forward each value into the matching setter on itself, but it only needs the Reader interface at the call site — so Reader is forward-declared here rather than included, keeping the writer header decoupled from the full reader hierarchy.

Relationships

Writer — setFrom(const Reader* source, ...) copies all data from a Reader instance into the Writer, respecting the given DataLayer and UnknownLayerPolicy.

`class DNAAPI Writer : public RBFBehaviorWriter, public GeometryWriter, public MachineLearnedBehaviorExtWriter, public JointBehaviorMetadataWriter, public TwistSwingBehaviorWriter`

Abstract unified write interface for all DNA data layers. Use this as the base type when you need to write a complete DNA asset — it combines geometry, behavior, machine-learned behavior, RBF, joint metadata, and twist/swing writing into a single entry point.

When to use this

Reach for Writer when you need to mutate or construct a DNA asset. Use setFrom to bulk-copy an entire existing asset from a Reader — optionally restricting which layers are transferred via DataLayer. Note that the layer hierarchy cannot be written selectively at the class level; the unified interface is intentional.

Example

// Obtain a Writer instance (e.g., from BinaryStreamWriter factory)
dna::Writer* writer = dna::BinaryStreamWriter::create(stream, memRes);
const dna::Reader* reader = dna::BinaryStreamReader::create(inputStream, memRes);

// Copy all layers, preserving any unknown data
writer->setFrom(reader, dna::DataLayer::All, dna::UnknownLayerPolicy::Preserve);

// Copy only geometry, discarding unrecognized layers
writer->setFrom(reader, dna::DataLayer::Geometry, dna::UnknownLayerPolicy::Discard);

Parameters

Name	Type	Description
`source`	`const Reader*`	required — the DNA Reader to copy data from
`layer`	`DataLayer`	optional — limits which layers are transferred; defaults to `DataLayer::All`
`policy`	`UnknownLayerPolicy`	optional — whether unrecognized layers are preserved or discarded; defaults to `UnknownLayerPolicy::Preserve`
`memRes`	`MemoryResource*`	optional — memory resource for temporary allocations during the copy; defaults to `nullptr`

Watch out for

The Writer class intentionally cannot write only specific layers — the unified interface mirrors the Reader hierarchy by design. Use DataLayer in setFrom to control which layers are read from source, not which are written.
setFrom is implemented in the abstract base class itself and calls every getter on source then every matching setter on this. For large DNA assets, pass a MemoryResource to avoid heap fragmentation during the copy.

API Reference — dna/Writer

Reader