Allow empty continuation.

CouleeApps · jonathanslenders · commit fc86ff03fe43 · 2019-11-26T21:56:23.000+01:00
If continuation is an empty string, instead of ignoring it and aligning with
spaces, honor the non-None but empty value and don't align to the prompt width
with spaces.

This is helpful if you want to configure your prompt to allow multiline editing
and also want to copy the text directly from your terminal.

Commit edited by Jonathan Slenders.
diff --git a/prompt_toolkit/shortcuts/prompt.py b/prompt_toolkit/shortcuts/prompt.py
@@ -313,7 +313,8 @@ class PromptSession(Generic[_T]):
     :param prompt_continuation: Text that needs to be displayed for a multiline
         prompt continuation. This can either be formatted text or a callable
         that takes a `prompt_width`, `line_number` and `wrap_count` as input
-        and returns formatted text.
+        and returns formatted text. When this is `None` (the default), then
+        `prompt_width` spaces will be used.
     :param complete_style: ``CompleteStyle.COLUMN``,
         ``CompleteStyle.MULTI_COLUMN`` or ``CompleteStyle.READLINE_LIKE``.
     :param mouse_support: `bool` or :class:`~prompt_toolkit.filters.Filter`
@@ -367,7 +368,7 @@ def __init__(
             include_default_pygments_style: FilterOrBool = True,
             history: Optional[History] = None,
             clipboard: Optional[Clipboard] = None,
-            prompt_continuation: PromptContinuationText = '',
+            prompt_continuation: Optional[PromptContinuationText] = None,
             rprompt: AnyFormattedText = None,
             bottom_toolbar: AnyFormattedText = None,
             mouse_support: FilterOrBool = False,
@@ -1117,7 +1118,7 @@ def _get_continuation(
 
         # When the continuation prompt is not given, choose the same width as
         # the actual prompt.
-        if not continuation and is_true(self.multiline):
+        if continuation is None and is_true(self.multiline):
             continuation = ' ' * width
 
         return to_formatted_text(
