Legacy `Node`/`Link` classes not exported from `__init__.py`

[sumanjeet0012]

The legacy Node and Link classes in dag/dag.py are not exported from dag/__init__.py, but utils.py references them via node_to_link(). This creates an inconsistency where internal code uses classes that aren't part of the public API.

Problem

In dag/__init__.py:

from .block import Block
from .codec import BlockCodec, BlockDecoder, BlockEncoder, ...
from .ipld_model import CID, IPLDNode, Kind, ...
from .multicodec_codes import ...

# ← Node and Link are NOT exported

But in dag/utils.py:

def node_to_link(node: Any) -> Any:
    from .dag import Link, Node  # ← Imports from internal module

    if not isinstance(node, Node):
        raise TypeError("node should be an instance of type Node")

    return Link("", node.size, node.multihash)

Users can't use node_to_link() without also importing from the internal dag.dag module.

Proposed Solution

Either:

Option A: Export Node and Link from __init__.py:

from .dag import Node, Link

__all__ = [
    # ... existing exports ...
    "Node",
    "Link",
]

Option B: Deprecate node_to_link() and remove the legacy classes:

import warnings

def node_to_link(node: Any) -> Any:
    warnings.warn(
        "node_to_link() is deprecated. Use the Block/codec API instead.",
        DeprecationWarning,
        stacklevel=2,
    )
    # ...

Related

• Files: dag/__init__.py, dag/dag.py, dag/utils.py