AttrDict to bytes and bytes to AttrDict transform.

[plum.attrdict] Module Reference

The plum.attrdict module provides the ArrayX transform which converts bytes into an “attribute accessible” dictionary of values and a dictionary of values into bytes. The “attribute accessible” dictionary has normal dictionary behaviors but also offers access to the members of the dictionary using Python attribute syntax.

This reference page shows how to create and use an ArrayX transform for packing and unpacking bytes, a lighter weight method than a custom Structure subclass. This page also provides API details.

The examples shown on this page require the following setup:

>>> from plum.array import ArrayX
>>> from plum.attrdict import AttrDictX
>>> from plum.bigendian import uint8
>>> from plum.utilities import pack, unpack

Basic Use

The ArrayX transform accepts the following arguments:

members:dictionary of member names and formats
name:transform name (for representations including dump format column)

For example:

>>> revision_x = AttrDictX({"major": uint8, "minor": uint8})

Use the transform to specify a format when using the pack() and unpack() utility functions or when using other high level transforms:

>>> fmt = {"hardware_rev": revision_x, "software_rev": revision_x}
>>> bindata = pack({"hardware_rev": dict(major=1, minor=0), "software_rev": dict(major=7, minor=2)}, fmt)
>>> bindata.hex()
>>> revisions = unpack(fmt, bindata)
>>> revisions
{'hardware_rev': AttrDict(major=1, minor=0), 'software_rev': AttrDict(major=7, minor=2)}
>>> # AttrDict members accessible by index or by attribute
>>> hw_rev = revisions["hardware_rev"]
>>> hw_rev["major"]
>>> hw_rev.minor
>>> array_x = ArrayX(fmt=revision_x, dims=(2, ))
>>> bindata = pack([dict(major=1, minor=0), dict(major=7, minor=2)], fmt=array_x)
>>> bindata.hex()
>>> unpack(array_x, bindata)
[AttrDict(major=1, minor=0), AttrDict(major=7, minor=2)]

Usage Considerations

  • ItemsX offers the capability to pack and unpack dictionaries but doesn’t offer access to unpacked members via attribute syntax.
  • Structure subclasses facilitate IDE type ahead as well as better static code analysis for the members.
  • Instantiating an ArrayX is substantially faster than subclassing Structure.
  • Structure offers many more features (e.g. automatically sized members, member defaults, customized constructors, etc.)

API Reference

class plum.attrdict.AttrDictX(members: Union[Dict[str, Any], List[Tuple[str, Any]]], name: str = 'AttrDict')

AttrDict to bytes and bytes to AttrDict transform.


Transform format name (for repr and dump “Format” column).


Transform format size in bytes.

pack(value: Any) → bytes

Pack value as formatted bytes.

Raises:PackError if type error, value error, etc.
pack_and_dump(value: Any) → Tuple[bytes, plum.dump.Dump]

Pack value as formatted bytes and produce bytes summary.

Raises:PackError if type error, value error, etc.
unpack(buffer: bytes) → Any

Unpack value from formatted bytes.

Raises:UnpackError if insufficient bytes, excess bytes, or value error
unpack_and_dump(buffer: bytes) → Tuple[Any, plum.dump.Dump]

Unpack value from bytes and produce packed bytes summary.

Raises:UnpackError if insufficient bytes, excess bytes, or value error