[ENH] make main a bit more professionnal

Author: Bornlex

main.py

@@ -1,10 +1,16 @@
 #! /usr/bin/python3.5
 
+import sys
+
 from parser.parser import *
 from execution.execution import *
 
+ex = sys.modules['execution.execution']
+
+example_filename = 'examples/WIL/push_dup.ws'
+
 def get_loop_instructions():
-    return loop_instructions = [
+    return [
         ('push', 1),
         ('label', 0),
         'dup',
@@ -18,14 +24,20 @@ def get_loop_instructions():
         'end'
     ]
 
-def main():
-    pass
-
-if __name__ == '__main__':
-    filename = 'examples/WIL/push_dup.ws'
+def main(filename):
     p = Parser()
     c = open(filename, 'r').read()
     content = p.remove_forbidden_chars(c)
     instructions = p.parse(content)
     print(instructions)
     execute(instructions)
+
+def usage():
+    print('usage: ./main.py file_to_execute.ws')
+
+if __name__ == '__main__':
+    ex.DEBUG = False
+    if len(sys.argv) != 2:
+        usage()
+        sys.exit(1)
+    main(sys.argv[1])