Implement monkey patching callbacks in YamlFSM config

lib/tfw/yaml_fsm.py

@@ -1,3 +1,6 @@
+from subprocess import Popen
+from functools import partial
+
 import yaml
 from transitions import State
 
@@ -7,12 +10,32 @@ from tfw import FSMBase
 class YamlFSM(FSMBase):
     def __init__(self, config_file):
         self.config = self.parse_config(config_file)
-        self.states = [State(**state) for state in self.config['states']]
-        super(YamlFSM, self).__init__()
-        for transition in self.config['transitions']:
-            self.machine.add_transition(**transition)
+        self.patch_config_callbacks()
+        self.setup_states()
+        super(YamlFSM, self).__init__()  # FSMBase.__init__() requires states
+        self.setup_transitions()
 
     @staticmethod
     def parse_config(config_file):
         with open(config_file, 'r') as ifile:
             return yaml.load(ifile)
+
+    def setup_states(self):
+        self.states = [State(**state) for state in self.config['states']]
+
+    def setup_transitions(self):
+        for transition in self.config['transitions']:
+            self.machine.add_transition(**transition)
+
+    def patch_config_callbacks(self):
+        topatch = {'on_enter', 'on_exit', 'prepare', 'before', 'after'}
+
+        for array in {'states', 'transitions'}:
+            for i, json_obj in enumerate(self.config[array]):
+                for attribute, value in json_obj.items():
+                    if attribute in topatch:
+                        self.config[array][i][attribute] = partial(self.run, value)
+
+    @staticmethod
+    def run(command, event):
+        Popen(command, shell=True)