cmds.projects.CmdCreateFile: Add --field-separator option

List values in a rendered template are joined with a fixed separator of
",\n" (comma plus newline), and there is no way to change that. Templates
sometimes want a different separator, e.g. a plain newline or a single-line
comma-separated list.

Add a --field-separator option that controls how list values are joined
in the rendered output. %n expands to a newline, and the default remains
",\n" for both formats. render_tmpl() applies the separator to the rendered
template, while render_pyright() rejects any other value: the built-in
pyrightconfig.json template is a fixed JSON document, and no alternative
separator is supported for it.

Update the help output test expectation accordingly.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.85.1
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/cmds/projects/CmdCreateFile.py

@@ -55,32 +55,56 @@ class CmdCreateFile(Cmd):  # export
         p = 'render_'
         return [name.removeprefix(p) for name in dir(self) if name.startswith(p)]
 
+    def __format_separator(self, separator: str | None, default: str) -> str:
+        if separator is None:
+            return default
+        format_chars = {
+            '%n': '\n',
+        }
+        for src, dst in format_chars.items():
+            separator = separator.replace(src, dst)
+        return separator
+
     def __render(
         self,
         template_name: str,
         values: list[RenderValues],
         li_quote: bool = False,
-        li_delimiter: str = '\n',
+        li_separator: str = '\n',
     ) -> str:
         return tmpl_render(
             template_name,
             values,
             li_quote = li_quote,
-            li_delimiter = li_delimiter,
+            li_delimiter = li_separator,
             search_path = self.app.args.search_path.split(':'),
         )
 
-    def render_tmpl(self, module: str, extra_fields: RenderValues) -> str:
+    def render_tmpl(
+        self,
+        module: str,
+        extra_fields: RenderValues,
+        separator: str | None,
+    ) -> str:
         template_name = self.app.args.template_name
         if template_name is None:
             raise Exception('Can\'t render template without name')
         return self.__render(
-            template_name, [extra_fields],
+            template_name,
+            [extra_fields],
             li_quote = self.app.args.quote,
-            li_delimiter = ',\n'
+            li_separator = self.__format_separator(separator, ',\n'),
         )
 
-    def render_pyright(self, module: str, extra_fields: RenderValues) -> str:
+    def render_pyright(
+        self,
+        module: str,
+        extra_fields: RenderValues,
+        separator: str | None,
+    ) -> str:
+        separator = self.__format_separator(separator, ',\n')
+        if separator != ',\n':
+            raise Exception(f'Unsupported separator for pyright config: "{separator}"')
         extra_paths = []
         for m in self.__jw_required(include_self = True):
             path = self.app.find_dir(m, search_subdirs = ['src/python', 'tools/python'])
@@ -94,7 +118,7 @@ class CmdCreateFile(Cmd):  # export
         return self.__render(
             'pyrightconfig.json', [values, extra_fields],
             li_quote = True,
-            li_delimiter = ',\n'
+            li_separator = ',\n'
         )
 
     def __init__(self, parent: Parent) -> None:
@@ -142,6 +166,13 @@ class CmdCreateFile(Cmd):  # export
                 'rendering output'
             )
         )
+        parser.add_argument(
+            '--field-separator',
+            help = (
+                'Field separator. %%n expands to newline. Default value depends on '
+                '--format'
+            )
+        )
         parser.add_argument('module', help = 'The module to generate the file for')
 
     @override
@@ -166,4 +197,4 @@ class CmdCreateFile(Cmd):  # export
             raise Exception(f'Unsupported output format {args.format}')
 
         # -- Render
-        sys.stdout.write(method(args.module, fields))
+        sys.stdout.write(method(args.module, fields, args.field_separator))