DeformableMirror: require n_actuators instead of _n_actuators.

Replaces the documented requirement for concrete implementations to
have a `_n_actuators` property and instead make the `n_actuators` an
abstract property.  This is better because:

1) it is enforced by abc instead of being just documented

2) one less property required.  For example, mirao is always 52 and is
defined on the library, and for bmc it is a field of the DM struct.

3) mypy does not like the use of the private property by the ABC which
is not declared on the ABC.

Author: carandraug

NEWS

@@ -17,6 +17,11 @@ Version 0.4.0 (upcoming)
     * The `Device._logger` attribute has been removed.  It is
       recommended to use a logger for the module.
 
+  * DeformableMirror:
+
+    * Concrete classes must implement the `n_actuators` public
+      property instead of the private _n_actuators`.
+
 * The device server and clients no longer force pickle protocol
   version 2.  If the client and server are running different Python
   versions it may be necessary to specify a version number.  This

microscope/devices.py

@@ -941,23 +941,19 @@ class DeformableMirror(Device, metaclass=abc.ABCMeta):
     def __init__(self, **kwargs) -> None:
         """Constructor.
 
-        Subclasses must define the following properties during
-        construction:
-
-            _n_actuators : int
-
-        In addition, the private properties `_patterns` and
-        `_pattern_idx` are initialized to None to support the queueing
-        of patterns and software triggering.
+        The private properties `_patterns` and `_pattern_idx` are
+        initialized to `None` to support the queueing of patterns and
+        software triggering.
         """
         super().__init__(**kwargs)
 
         self._patterns = None # type: typing.Optional[numpy.ndarray]
         self._pattern_idx = -1 # type: int
 
     @property
+    @abc.abstractmethod
     def n_actuators(self) -> int:
-        return self._n_actuators
+        raise NotImplementedError()
 
     def _validate_patterns(self, patterns: numpy.ndarray) -> None:
         """Validate the shape of a series of patterns.
@@ -971,10 +967,10 @@ def _validate_patterns(self, patterns: numpy.ndarray) -> None:
         if patterns.ndim > 2:
             raise Exception("PATTERNS has %d dimensions (must be 1 or 2)"
                             % patterns.ndim)
-        elif patterns.shape[-1] != self._n_actuators:
+        elif patterns.shape[-1] != self.n_actuators:
             raise Exception(("PATTERNS length of second dimension '%d' differs"
                              " differs from number of actuators '%d'"
-                             % (patterns.shape[-1], self._n_actuators)))
+                             % (patterns.shape[-1], self.n_actuators)))
 
     @abc.abstractmethod
     def apply_pattern(self, pattern: numpy.ndarray) -> None:

microscope/mirror/alpao.py

@@ -124,6 +124,10 @@ def __init__(self, serial_number, **kwargs):
         self._trigger_type = TriggerType.SOFTWARE
         self._trigger_mode = TriggerMode.ONCE
 
+    @property
+    def n_actuators(self) -> int:
+        return self._n_actuators
+
     def apply_pattern(self, pattern):
         self._validate_patterns(pattern)
         pattern = self._normalize_patterns(pattern)

microscope/mirror/bmc.py

@@ -42,7 +42,9 @@ def __init__(self, serial_number, **kwargs):
         if status:
             raise Exception(BMC.ErrorString(status))
 
-        self._n_actuators = self._dm.ActCount
+    @property
+    def n_actuators(self) -> int:
+        return self._dm.ActCount
 
     def apply_pattern(self, pattern):
         self._validate_patterns(pattern)

microscope/mirror/mirao52e.py

@@ -58,10 +58,6 @@ def __init__(self, **kwargs) -> None:
         if not mro.open(self._status):
             self._raise_status(mro.open)
 
-        ## super class needs this, but maybe it should be calling the
-        ## property directly?
-        self._n_actuators = mro.NB_COMMAND_VALUES # type: int
-
     @property
     def n_actuators(self) -> int:
         return mro.NB_COMMAND_VALUES

microscope/testsuite/devices.py

@@ -376,6 +376,10 @@ def __init__(self, n_actuators, **kwargs):
         super().__init__(**kwargs)
         self._n_actuators = n_actuators
 
+    @property
+    def n_actuators(self) -> int:
+        return self._n_actuators
+
     def apply_pattern(self, pattern):
         self._validate_patterns(pattern)
         self._current_pattern = pattern