Function `compile_authwords()` no longer has side effects

Closes #185

patacrep/authors.py

@@ -5,8 +5,6 @@ import re
 
 LOGGER = logging.getLogger(__name__)
 
-AUTHWORDS_KEYS = ["after", "ignore", "separators"]
-
 RE_AFTER = r"^.*\b{}\b(.*)$"
 RE_SEPARATOR = r"^(.*)\b *{} *(\b.*)?$"
 
@@ -15,23 +13,17 @@ def compile_authwords(authwords):
 
     This regexp will later be used to match these words in authors strings.
     """
-    # Fill missing values
-    for key in AUTHWORDS_KEYS:
-        if key not in authwords:
-            authwords[key] = []
-
-    # Compilation
-    authwords['after'] = [
+    return {
+        'ignore': authwords.get('ignore', []),
+        'after': [
             re.compile(RE_AFTER.format(word), re.LOCALE)
             for word in authwords['after']
-        ]
-    authwords['separators'] = [
+            ],
+        'separators': [
             re.compile(RE_SEPARATOR.format(word), re.LOCALE)
             for word in ([" %s" % word for word in authwords['separators']] + [',', ';'])
-        ]
-
-    return authwords
-
+            ],
+        }
 
 def split_author_names(string):
     r"""Split author between first and last name.

patacrep/build.py

@@ -1,7 +1,6 @@
 """Build a songbook, according to parameters found in a .sb file."""
 
 import codecs
-import copy
 import glob
 import logging
 import threading
@@ -85,9 +84,7 @@ class Songbook(object):
 
         config['_template'] = renderer.get_all_variables(self.config.get('template', {}))
 
-        config['_compiled_authwords'] = authors.compile_authwords(
-            copy.deepcopy(config['authors'])
-            )
+        config['_compiled_authwords'] = authors.compile_authwords(config['authors'])
 
         # Loading custom plugins
         config['_content_plugins'] = files.load_plugins(