From ef6a1167b059301b1f186497efcac3fd67ad48a3 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Fri, 16 Dec 2022 00:00:46 -0500
Subject: [PATCH] `Viz._index_field` a `typing.Literal[str]`

---
 piker/ui/_dataviz.py | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/piker/ui/_dataviz.py b/piker/ui/_dataviz.py
index bec5481f..82cc2e37 100644
--- a/piker/ui/_dataviz.py
+++ b/piker/ui/_dataviz.py
@@ -21,6 +21,7 @@ Data vizualization APIs
 from __future__ import annotations
 from typing import (
     Optional,
+    Literal,
     TYPE_CHECKING,
 )
 
@@ -243,8 +244,16 @@ class Viz(msgspec.Struct):  # , frozen=True):
     is_ohlc: bool = False
     render: bool = True  # toggle for display loop
 
-    # _index_field: str = 'index'
-    _index_field: str = 'time'
+    _index_field: Literal[
+        'index',
+        'time',
+
+        # TODO: idea is to re-index all time series to a common
+        # longest-len-int-index where we avoid gaps and instead
+        # graph on the 0 -> N domain of the array index super set.
+        # 'gapless',
+
+    ] = 'time'
 
     # downsampling state
     _last_uppx: float = 0