Exec Control: Copied to WA3 and now uses default environment.

Moved execution decorators from wlauto to wa.
Modified to use a default environment if none is explicitly specified.

wa/utils/exec_control.py

@@ -0,0 +1,110 @@
+from inspect import getmro
+
+# "environment" management:
+__environments = {}
+__active_environment = None
+
+
+def activate_environment(name):
+    """
+    Sets the current tracking environment to ``name``. If an
+    environment with that name does not already exist, it will be
+    created.
+    """
+    #pylint: disable=W0603
+    global __active_environment
+
+    if name not in __environments.keys():
+        init_environment(name)
+    __active_environment = name
+
+def init_environment(name):
+    """
+    Create a new environment called ``name``, but do not set it as the
+    current environment.
+
+    :raises: ``ValueError`` if an environment with name ``name``
+             already exists.
+    """
+    if name in __environments.keys():
+        msg = "Environment {} already exists".format(name)
+        raise ValueError(msg)
+    __environments[name] = []
+
+def reset_environment(name=None):
+    """
+    Reset method call tracking for environment ``name``. If ``name`` is
+    not specified or is ``None``, reset the current active environment.
+
+    :raises: ``ValueError`` if an environment with name ``name``
+          does not exist.
+    """
+
+    if name is not None:
+        if name not in __environments.keys():
+            msg = "Environment {} does not exist".format(name)
+            raise ValueError(msg)
+        __environments[name] = []
+    else:
+        if __active_environment is None:
+            activate_environment('default')
+        __environments[__active_environment] = []
+
+# The decorators:
+def once_per_instance(method):
+    """
+    The specified method will be invoked only once for every bound
+    instance within the environment.
+    """
+    def wrapper(*args, **kwargs):
+        if __active_environment is None:
+            activate_environment('default')
+        func_id = repr(args[0])
+        if func_id in __environments[__active_environment]:
+            return
+        else:
+            __environments[__active_environment].append(func_id)
+        return method(*args, **kwargs)
+
+    return wrapper
+
+def once_per_class(method):
+    """
+    The specified method will be invoked only once for all instances
+    of a class within the environment.
+    """
+    def wrapper(*args, **kwargs):
+        if __active_environment is None:
+            activate_environment('default')
+
+        func_id = repr(method.func_name) + repr(args[0].__class__)
+
+        if func_id in __environments[__active_environment]:
+            return
+        else:
+            __environments[__active_environment].append(func_id)
+        return method(*args, **kwargs)
+
+    return wrapper
+
+def once(method):
+    """
+    The specified method will be invoked only once within the
+    environment.
+    """
+    def wrapper(*args, **kwargs):
+        if __active_environment is None:
+            activate_environment('default')
+
+        func_id = repr(method.func_name)
+        # Store the least derived class, which isn't object, to account
+        # for subclasses.
+        func_id += repr(getmro(args[0].__class__)[-2])
+
+        if func_id in __environments[__active_environment]:
+            return
+        else:
+            __environments[__active_environment].append(func_id)
+        return method(*args, **kwargs)
+
+    return wrapper