Resolve #2021 "04 16 branched from master ini file device"

Completed ini example. Don't merge before !23 (merged). Small unrelated change slipped in to this branch, will need to fix that first.

devices/clients/ini_client.py

+from src.comms_client import *
+import configparser
+import numpy
+
+
+numpy_to_ini_dict = {
+    numpy.int64: int,
+    numpy.double: float,
+    numpy.bool_: bool,
+    str: str
+}
+ini_to_numpy_dict = {
+    int: numpy.int64,
+    float: numpy.double,
+    bool: numpy.bool_,
+    str: str
+}
+
+import os
+
+
+class ini_client(CommClient):
+    """
+    this class provides an example implementation of a comms_client.
+    Durirng initialisation it creates a correctly shaped zero filled value. on read that value is returned and on write its modified.
+    """
+
+    def start(self):
+        super().start()
+
+    def __init__(self, filename, fault_func, streams, try_interval=2):
+        """
+        initialises the class and tries to connect to the client.
+        """
+        self.config = configparser.ConfigParser()
+        self.filename = filename
+
+        if not filename.endswith(".ini"):
+            filename = filename + ".ini"
+
+
+        super().__init__(fault_func, streams, try_interval)
+
+        # Explicitly connect
+        if not self.connect():
+            # hardware or infra is down -- needs fixing first
+            fault_func()
+            return
+
+    def connect(self):
+        files_path = [os.path.abspath(x) for x in os.listdir()]
+        self.streams.debug_stream(" %s", files_path)
+        self.config_file = open(self.filename, "rw")
+
+        self.connected = True  # set connected to true
+        return True  # if succesfull, return true. otherwise return false
+
+    def disconnect(self):
+        self.connected = False  # always force a reconnect, regardless of a successful disconnect
+        self.streams.debug_stream("disconnected from the 'client' ")
+
+    def _setup_annotation(self, annotation):
+        """
+        this function gives the client access to the comm client annotation data given to the attribute wrapper.
+        The annotation data can be used to provide whatever extra data is necessary in order to find/access the monitor/control point.
+
+        the annotation can be in whatever format may be required. it is up to the user to handle its content
+        example annotation may include:
+        - a file path and file line/location
+        - COM object path
+        """
+
+        # as this is an example, just print the annotation
+        self.streams.debug_stream("annotation: {}".format(annotation))
+        name = annotation.get('name')
+        if name is None:
+            AssertionError("ini client requires a variable name to set/get")
+        section = annotation.get('section')
+        if section is None:
+            AssertionError("requires a section to open")
+
+        return section, name
+
+
+    def _setup_value_conversion(self, attribute):
+        """
+        gives the client access to the attribute_wrapper object in order to access all
+        necessary data such as dimensionality and data type
+        """
+
+        if attribute.dim_y > 1:
+            dims = (attribute.dim_y, attribute.dim_x)
+        else:
+            dims = (attribute.dim_x,)
+
+        dtype = attribute.numpy_type
+
+        return dims, dtype
+
+    def _setup_mapping(self, name, section, dtype):
+        """
+        takes all gathered data to configure and return the correct read and write functions
+        """
+
+        def read_function():
+            value = self.config.get(section, name)
+            value = ini_to_numpy_dict[dtype](value)
+            return value
+
+        def write_function(write_value):
+            self.config.set(section, name, write_value)
+            fp = open(self.filename, 'w')
+            self.config.write(fp)
+
+        return read_function, write_function
+
+    def setup_attribute(self, annotation=None, attribute=None):
+        """
+        MANDATORY function: is used by the attribute wrapper to get read/write functions.
+        must return the read and write functions
+        """
+
+        # process the comms_annotation
+        section, name = self._setup_annotation(annotation)
+
+        # get all the necessary data to set up the read/write functions from the attribute_wrapper
+        dims, dtype = self._setup_value_conversion(attribute)
+
+        # configure and return the read/write functions
+        read_function, write_function = self._setup_mapping(name, section, dtype)
+
+        # return the read/write functions
+        return read_function, write_function