Options accepting a file should accept lists of files

The rationale is that these options readily accept multiple files from
the command line, because they can be specified multiple times. However,
duplicate option keys are invalid in an INI config file. Our alternative
here is to accept multiple comma-separated values for each option key,
in addition to mulitple occurrences of the same option key.

Author: DimitriPapadopoulos

codespell_lib/_codespell.py

@@ -395,10 +395,9 @@ def parse_options(
         "-D",
         "--dictionary",
         action="append",
-        help="custom dictionary file that contains spelling "
-        "corrections. If this flag is not specified or "
-        'equals "-" then the default dictionary is used. '
-        "This option can be specified multiple times.",
+        help="comma-separated list of custom dictionary files that "
+        "contain spelling corrections. If this flag is not specified "
+        'or equals "-" then the default dictionary is used.',
     )
     builtin_opts = "\n- ".join(
         [""] + [f"{d[0]!r} {d[1]}" for d in _builtin_dictionaries]
@@ -428,26 +427,26 @@ def parse_options(
         "-I",
         "--ignore-words",
         action="append",
-        metavar="FILE",
-        help="file that contains words that will be ignored "
-        "by codespell. File must contain 1 word per line."
-        " Words are case sensitive based on how they are "
-        "written in the dictionary file",
+        metavar="FILES",
+        help="comma-separated list of files that contain "
+        "words to be ignored by codespell. Files must contain "
+        "1 word per line. Words are case sensitive based on "
+        "how they are written in the dictionary file.",
     )
     parser.add_argument(
         "-L",
         "--ignore-words-list",
         action="append",
         metavar="WORDS",
-        help="comma separated list of words to be ignored "
+        help="comma-separated list of words to be ignored "
         "by codespell. Words are case sensitive based on "
-        "how they are written in the dictionary file",
+        "how they are written in the dictionary file.",
     )
     parser.add_argument(
         "--uri-ignore-words-list",
         action="append",
         metavar="WORDS",
-        help="comma separated list of words to be ignored "
+        help="comma-separated list of words to be ignored "
         "by codespell in URIs and emails only. Words are "
         "case sensitive based on how they are written in "
         'the dictionary file. If set to "*", all '
@@ -499,11 +498,13 @@ def parse_options(
     parser.add_argument(
         "-x",
         "--exclude-file",
+        action="append",
         type=str,
-        metavar="FILE",
-        help="ignore whole lines that match those "
-        "in the file FILE. The lines in FILE "
-        "should match the to-be-excluded lines exactly",
+        metavar="FILES",
+        help="ignore whole lines that match those in "
+        "the comma-separated list of files EXCLUDE. "
+        "The lines in these files should match the "
+        "to-be-excluded lines exactly",
     )
 
     parser.add_argument(
@@ -1097,6 +1098,18 @@ def parse_file(
     return bad_count
 
 
+def flatten_comma_separated_arguments(
+    arguments: List[str],
+) -> List[str]:
+    """
+    >>> flatten_comma_separated_arguments(["a,b,c", "d", "e"])
+    ['a', 'b', 'c', 'd', 'e']
+    >>> flatten_comma_separated_arguments([])
+    []
+    """
+    return [item for argument in arguments for item in argument.split(",")]
+
+
 def _script_main() -> int:
     """Wrap to main() for setuptools."""
     return main(*sys.argv[1:])
@@ -1148,20 +1161,20 @@ def main(*args: str) -> int:
     else:
         ignore_word_regex = None
 
-    ignore_words_files = options.ignore_words or []
     ignore_words, ignore_words_cased = parse_ignore_words_option(
         options.ignore_words_list
     )
-
-    for ignore_words_file in ignore_words_files:
-        if not os.path.isfile(ignore_words_file):
-            print(
-                f"ERROR: cannot find ignore-words file: {ignore_words_file}",
-                file=sys.stderr,
-            )
-            parser.print_help()
-            return EX_USAGE
-        build_ignore_words(ignore_words_file, ignore_words, ignore_words_cased)
+    if options.ignore_words:
+        ignore_words_files = flatten_comma_separated_arguments(options.ignore_words)
+        for ignore_words_file in ignore_words_files:
+            if not os.path.isfile(ignore_words_file):
+                print(
+                    f"ERROR: cannot find ignore-words file: {ignore_words_file}",
+                    file=sys.stderr,
+                )
+                parser.print_help()
+                return EX_USAGE
+            build_ignore_words(ignore_words_file, ignore_words, ignore_words_cased)
 
     uri_regex = options.uri_regex or uri_regex_def
     try:
@@ -1178,7 +1191,7 @@ def main(*args: str) -> int:
         itertools.chain(*parse_ignore_words_option(options.uri_ignore_words_list))
     )
 
-    dictionaries = options.dictionary or ["-"]
+    dictionaries = flatten_comma_separated_arguments(options.dictionary or ["-"])
 
     use_dictionaries = []
     for dictionary in dictionaries:
@@ -1243,7 +1256,9 @@ def main(*args: str) -> int:
 
     exclude_lines: Set[str] = set()
     if options.exclude_file:
-        build_exclude_hashes(options.exclude_file, exclude_lines)
+        exclude_files = flatten_comma_separated_arguments(options.exclude_file)
+        for exclude_file in exclude_files:
+            build_exclude_hashes(exclude_file, exclude_lines)
 
     file_opener = FileOpener(options.hard_encoding_detection, options.quiet_level)
 

pyproject.toml

@@ -161,6 +161,6 @@ max-complexity = 45
 [tool.ruff.lint.pylint]
 allow-magic-value-types = ["bytes", "int", "str",]
 max-args = 13
-max-branches = 49
+max-branches = 51
 max-returns = 11
 max-statements = 113