added a call to an initialize function to generic_cylinders per a sug…

doc/src/generic_cylinders.rst

@@ -42,3 +42,34 @@ ignored.
    probably needed on the command line. Consistency with the files in the
    pickle directory might not be checked by the program.
 
+A Class in the module
+---------------------
+
+If you want to have a class in the module to help create return values
+for functions, you will need to have an additional helper file called
+``initialize(cfg)``. It is called by ``generic_cylinders.py``
+after cfg is populated and can
+be used to create a class. Note that the function ``inparser_adder`` cannot
+make use of the class because that function is called before ``initialize``.
+Here is some sudo-code for this idea:
+
+.. code_block:: python
+
+    my_object = None
+
+    def inparser_adder(cfg):
+        cfg.add_to_config('json_file_with_model_params',
+                      ...)
+
+    def initalize(cfg):
+        global my_object
+        my_object = MyClass(cfg)
+
+    def scenario_names_creator(num_scens,...):
+        return my_object.scenario_names_creator(num_scens,...)
+
+    def scenario_creator(scen_name, ...):
+        return my_object.scenario_creator(scen_name, ...)
+
+def scenario_denouement(rank, ...):
+    return my_object.scenario_denoument(rank, ...)   

examples/sizes/sizes.py

@@ -82,6 +82,11 @@ def sample_tree_scen_creator(sname, stage, sample_branching_factors, seed,
     sca["num_scens"] = sample_branching_factors[0]  # two-stage problem
     return scenario_creator(sname, **sca)
 
+def initialize(cfg):
+    print("initialize was successfully called."
+          " BTW: it does nothing for the sizes problem,"
+          " it is just here for testing purposes.")
+
 ######## end helper functions #########
 
 ########## a customized rho setter #############

mpisppy/generic_cylinders.py

@@ -544,9 +544,13 @@ def _proper_bundles(cfg):
         fname = os.path.basename(model_fname)
         sys.path.append(dpath)
         module = importlib.import_module(fname)
-    
+
     cfg = _parse_args(module)
 
+    # the initialize function is particularly useful for a class in the module
+    if hasattr(module, "initialize"):
+        module.initialize(cfg)
+
     bundle_wrapper = None  # the default
     if _proper_bundles(cfg):
         # TBD: remove the need for dill if you are not reading or writing