Method _run_diff

lib/sqlalchemy/util/tool_support.py:154–181

(
        self,
        destination_path: Union[str, Path],
        *,
        source: Optional[str] = None,
        source_file: Optional[str] = None,
    )

            self.write_status("done\n")

    def _run_diff(
        self,
        destination_path: Union[str, Path],
        *,
        source: Optional[str] = None,
        source_file: Optional[str] = None,
    ) -> None:
        if source_file:
            with open(source_file, encoding="utf-8") as tf:
                source_lines = list(tf)
        elif source is not None:
            source_lines = source.splitlines(keepends=True)
        else:
            assert False, "source or source_file is required"

        with open(destination_path, encoding="utf-8") as dp:
            d = difflib.unified_diff(
                list(dp),
                source_lines,
                fromfile=Path(destination_path).as_posix(),
                tofile="<proposed changes>",
                n=3,
                lineterm="\n",
            )
            d_as_list = list(d)
            if d_as_list:
                self.diffs_detected = True
                print("".join(d_as_list))

    @contextlib.contextmanager
    def add_arguments(self) -> Iterator[ArgumentParser]: