add context manager for parameters (#748)

* add context manager for parameters

* add context manager for parameters

cid/test/python/test_isolated_parameters.py

@@ -0,0 +1,12 @@
+from cid.utils import IsolatedParameters, get_parameters, set_parameters
+
+def test_isolated_parameter_context():
+    """ make sure the isolated_parameter works
+    """
+    set_parameters({'param': 'a'})
+
+    with IsolatedParameters():
+        set_parameters({'param': 'b'})
+        assert get_parameters().get('param') == 'b', 'parameters within context must be B'
+
+    assert get_parameters().get('param') == 'a', 'parameters within context must be A'

cid/utils.py

@@ -1,5 +1,6 @@
 import os
 import sys
+import copy
 import math
 import inspect
 import logging
@@ -279,6 +280,15 @@ def ago(time):
     return 'just now'
 
 
+class IsolatedParameters:
+    """A context manager to run something in isolated set of parameters"""
+    def __enter__(self):
+        self.backup = copy.deepcopy(params)
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        global params
+        params = self.backup
+
 def merge_objects(obj1, obj2, depth=2):
     """ merging objects with a depth