SoftPositioner is not identified as device or signal using walk_components()

[prjemian]

While exploring a resolution to https://github.com/BCDA-APS/apstools/issues/641, tested the proposed solution there to a diffractometer instance from hklpy, such as:

import hkl

sim4c = hkl.SimulatedE4CV("", name="sim4c")

Using the walk_components() method, it is possible to print a small table showing if a Component is either a device or a signal:

import pyRestTable

table = pyRestTable.Table()
table.labels = "dotted_name is_device  is_signal".split()
for item in sim4c.walk_components():
    table.addRow((item.dotted_name,item.item.is_device, item.item.is_signal))    
print(table.reST(fmt="md"))

This table is printed:

dotted_name	is_device	is_signal
energy	False	True
energy_units	False	True
energy_offset	False	True
energy_update_calc_flag	False	True
geometry_name	False	True
class_name	False	True
sample_name	False	True
lattice	False	True
lattice_reciprocal	False	True
U	False	True
UB	False	True
reflections	False	True
reflections_details	False	True
ux	False	True
uy	False	True
uz	False	True
diffractometer_name	False	True
_hklpy_version	False	True
_pseudos	False	True
_reals	False	True
_constraints	False	True
_mode	False	True
orientation_attrs	False	True
max_forward_iterations	False	True
h	True	False
h.readback	False	True
h.setpoint	False	True
k	True	False
k.readback	False	True
k.setpoint	False	True
l	True	False
l.readback	False	True
l.setpoint	False	True
omega	False	False
chi	False	False
phi	False	False
tth	False	False

Note that omega, chi, phi, and tth that both columns are False. It is expected that each of these SoftPositioners would be identified as is_device=True.

[prjemian]

For reference: SoftPositioner, walk_components(), is_device, and is_signal

[prjemian]

Looking at PositionerBase, it is not clear whether this might be used as a Device or as a Signal, so the test: https://github.com/bluesky/ophyd/blob/ac6251131b4638c715ce8b90478a0d714cb857d3/ophyd/device.py#L215-L218

returns False since it is not a subclass of Device. Similarly, this cannot be a Signal since it is not subclass: https://github.com/bluesky/ophyd/blob/ac6251131b4638c715ce8b90478a0d714cb857d3/ophyd/device.py#L220-L223

Perhaps the test for is_device could consider if the object in question as Component attributes. Wouldn't this determine whether the object is or is not a Device? And the test for is_signal would verify that the class does not have Component attributes.

[prjemian]

In [130]: dir(sim4c.omega)
Out[130]: 
['SUB_DONE',
 'SUB_READBACK',
 'SUB_START',
 '_OphydObject__any_instantiated',
 '_OphydObject__instantiation_callbacks',
 '_OphydObject__register_instance',
 '_SUB_REQ_DONE',
 '__annotations__',
 '__class__',
 '__copy__',
 '__delattr__',
 '__dict__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__getnewargs_ex__',
 '__gt__',
 '__hash__',
 '__init__',
 '__init_subclass__',
 '__le__',
 '__lt__',
 '__module__',
 '__ne__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 '_args_cache',
 '_attr_name',
 '_callbacks',
 '_cb_count',
 '_cid_to_event_mapping',
 '_default_sub',
 '_done_moving',
 '_egu',
 '_kind',
 '_limits',
 '_mark_as_instantiated',
 '_moving',
 '_name',
 '_ophyd_labels_',
 '_parent',
 '_position',
 '_repr_info',
 '_reset_sub',
 '_run_subs',
 '_set_position',
 '_settle_time',
 '_setup_move',
 '_started_moving',
 '_timeout',
 '_unwrapped_callbacks',
 '_validate_kind',
 'add_instantiation_callback',
 'attr_name',
 'check_value',
 'clear_sub',
 'connected',
 'control_layer_log',
 'describe',
 'describe_configuration',
 'destroy',
 'dotted_name',
 'egu',
 'event_types',
 'high_limit',
 'hints',
 'kind',
 'limits',
 'log',
 'low_limit',
 'move',
 'moving',
 'name',
 'parent',
 'position',
 'read',
 'read_configuration',
 'report',
 'root',
 'set',
 'settle_time',
 'source',
 'stop',
 'subscribe',
 'subscriptions',
 'timeout',
 'unsubscribe',
 'unsubscribe_all']

Does not look like a Device to me since it has no Component attributes. Also:

In [131]: sim4c.omega.read()
Out[131]: OrderedDict([('sim4c_omega', {'value': 0, 'timestamp': 1677266815.4288268})])

[prjemian]

Perhaps, leave is_device as-is and make is_signal be not _is_device. Such as:

 @property 
 def is_signal(self): 
     "Does this Component contain a Signal?" 
     return isinstance(self.cls, type) and not self.is_device