feature/black command line args

CHANGES.rst

@@ -1,8 +1,8 @@
-0.3.0.dev / 2020-06-22
+0.3.0 / 2020-06-22
 ----------------------
 
 - Feature: Add support for black config
-
+- Feature: Add support for ``-l``/``--line-length`` and ``-S``/``--skip-string-normalization``
 
 0.2.0 / 2020-03-11
 ------------------

CONTRIBUTORS.rst

@@ -6,3 +6,4 @@
 
 - Alexander Tishin (@Mystic-Mirage)
 - Antti Kaihola (@akaihola)
+- Correy Lim (@CorreyL)

README.rst

@@ -94,6 +94,20 @@ Example:
 
    if False: print('there')
 
+Black Command Line Arguments
+============================
+
+``black`` `command line arguments`_ that are currently supported:
+
+.. code-block:: shell
+
+     -S, --skip-string-normalization
+                           Sets the `--skip-string-normalization` flag for
+                           `black`
+     -l LINE_LENGTH, --line-length LINE_LENGTH
+                           Sets the `--line-length` argument for `black`
+
+.. _command line arguments: https://black.readthedocs.io/en/stable/installation_and_usage.html#command-line-options
 
 Editor integration
 ==================

src/darker/__main__.py

@@ -21,7 +21,7 @@
 
 
 def format_edited_parts(
-    srcs: Iterable[Path], isort: bool, config: Optional[str]
+    srcs: Iterable[Path], isort: bool, black_args: dict, config: Optional[str]
 ) -> None:
     """Black (and optional isort) formatting for chunks with edits since the last commit
 
@@ -42,6 +42,7 @@ def format_edited_parts(
 
     :param srcs: Directories and files to re-format
     :param isort: ``True`` to also run ``isort`` first on each changed file
+    :param black_args: Command-line arguments to send to ``black.FileMode``
     :param config: Path to the black configuration file (optional)
 
     """
@@ -68,7 +69,7 @@ def format_edited_parts(
                 continue
 
             # 4. run black
-            edited, formatted = run_black(src, config)
+            edited, formatted = run_black(src, black_args, config)
             logger.debug("Read %s lines from edited file %s", len(edited), src)
             logger.debug("Black reformat resulted in %s lines", len(formatted))
 
@@ -136,8 +137,14 @@ def main(argv: List[str] = None) -> None:
         logger.error(f"{ISORT_INSTRUCTION} to use the `--isort` option.")
         exit(1)
 
+    black_args = {}
+    if args.line_length:
+        black_args["line_length"] = args.line_length
+    if args.skip_string_normalization:
+        black_args["skip_string_normalization"] = args.skip_string_normalization
+
     paths = {Path(p) for p in args.src}
-    format_edited_parts(paths, args.isort, args.config)
+    format_edited_parts(paths, args.isort, black_args, args.config)
 
 
 if __name__ == "__main__":

src/darker/black_diff.py

@@ -99,14 +99,31 @@ def read_black_config(src: Path, value: Optional[str]) -> Dict[str, Any]:
     return context.default_map or {}
 
 
-def run_black(src: Path, config: Optional[str]) -> Tuple[List[str], List[str]]:
+def run_black(src: Path, black_args: dict, config: Optional[str]) -> Tuple[List[str], List[str]]:
     """Run the black formatter for the contents of the given Python file
 
     Return lines of the original file as well as the formatted content.
 
+    :param black_args: Command-line arguments to send to ``black.FileMode``
+
     """
     defaults = read_black_config(src, config)
-    mode = FileMode(**defaults)
+
+    command_line_args = {}
+    if "line_length" in black_args:
+        command_line_args["line_length"] = black_args["line_length"]
+    if "skip_string_normalization" in black_args:
+        # The ``black`` command line argument is
+        # ``--skip-string-normalization``, but the parameter for
+        # ``black.FileMode`` needs to be the opposite boolean of
+        # ``skip-string-normalization``, hence the inverse boolean
+        command_line_args["string_normalization"] = not black_args[
+            "skip_string_normalization"
+        ]
+
+    # Override defaults and pyproject.toml settings if they've been specified
+    # from the command line arguments
+    mode = FileMode(**{**defaults, **command_line_args})
 
     src_contents = src.read_text()
     dst_contents = format_str(src_contents, mode=mode)

src/darker/command_line.py

@@ -55,4 +55,18 @@ def parse_command_line(argv: List[str]) -> Namespace:
     parser.add_argument(
         "--version", action="store_true", help="Show the version of `darker`"
     )
+    parser.add_argument(
+        "-S",
+        "--skip-string-normalization",
+        action="store_true",
+        dest="skip_string_normalization",
+        help="Don't normalize string quotes or prefixes",
+    )
+    parser.add_argument(
+        "-l",
+        "--line-length",
+        type=int,
+        dest="line_length",
+        help="How many characters per line to allow [default: 88]",
+    )
     return parser.parse_args(argv)