DAQ Policy
==========
Not every parameter of a device is interesting to record, such as the provided scenes.
As such, the policy for each individual property can be set, on a per-instance basis.

These are specified using the :class:`DAQPolicy` enum:
 - `OMIT`: will not record the property to file;
 - `SAVE`: will record the property to file;
 - `UNSPECIFIED`: will adopt the global default DAQ policy. Currently, it is set to
   record, although this will eventually change to not recorded.

Legacy devices which do not specify a policy will have an `UNSPECIFIED` policy set
to all their properties.

.. note::
    This are applied to leaf properties. Nodes do not have DAQPolicy.

Developers should liaise with users to define which properties should be recorded.
These can be set up programmatically:

.. code-block:: Python

   from karabo.bound import DAQPolicy, MetricPrefix, UINT32_ELEMENT

   @staticmethod
   def expectedParameters(expected):
       (
           UINT32_ELEMENT(expected).key('enzymAssay')
               .displayedName("Assay")
               .descriptio("Enzym Activity")
               .unit(Unit.KATAL)
               .metricPrefix(MetricPrefix.MICRO)
               .daqPolicy(DAQPolicy.SAVE)
               .readOnly().initialValue(0)
               .commit(),
       )

The policy can be overwritten from the GUI, before instantiation, and saved in a project:

.. image:: graphics/daq_policy.png

Injected properties, however, can only define their policy at the time of injection.