Fix Python < 3.6, add __slots__

decaylanguage/dec/dec.py

@@ -27,6 +27,13 @@ class DecFileParser(object):
     >>> parser = DecFileParser('my-decay-file.dec')
     >>> parser.parse()
     """
+
+    __slots__ = ("_grammar",
+                 "_grammar_info",
+                 "_decay_file",
+                 "_parsed_dec_file",
+                 "_parsed_decays")
+
     def __init__(self, decay_file):
         """
         Parser constructor.
@@ -36,6 +43,9 @@ def __init__(self, decay_file):
         decay_file: str
             Input .dec decay file.
         """
+        # Conversion to handle pathlib on Python < 3.6:
+        decay_file = str(decay_file)
+
         # Check input file
         if not os.path.exists(decay_file):
             raise FileNotFoundError("'{0}'!".format(decay_file))
@@ -99,11 +109,15 @@ def load_grammar(self, filename=None, parser='lalr', lexer='standard', **options
         See Lark's Lark class for a description of available options
         for parser, lexer and options.
         """
+
         if filename is None:
             filename = 'decfile.lark'
             with data.open_text(data, filename) as f:
                 self._grammar = f.read()
         else:
+            # Conversion to handle pathlib on Python < 3.6:
+            filename = str(filename)
+
             self._grammar = open(filename).read()
 
         self._grammar_info = dict(lark_file=filename, parser=parser, lexer=lexer, **options)

setup.py

@@ -73,7 +73,7 @@ def proc_readme(text):
         'pathlib2>=2.3; python_version<"3.5"',
         'enum34>=1.1; python_version<"3.4"',
         'importlib_resources>=1.0; python_version<"3.7"',
-        'particle'
+        'particle>=0.4.1'
     ],
     extras_require=extras,
     setup_requires=['pytest-runner'],

tests/test_dec.py

@@ -9,6 +9,12 @@
 from decaylanguage.dec.dec import DecFileParser
 from decaylanguage.dec.dec import DecFileNotParsed, DecayNotFound
 
+# New in Python 3
+try:
+    FileNotFoundError
+except NameError:
+    FileNotFoundError = IOError
+
 
 DIR = Path(__file__).parent.resolve()