...

docs/indicator-info.md

@@ -0,0 +1,33 @@
+# Indicator info meta-data
+
+
+## Model
+
+Info attributes are stored as dictionary items in the `info` attribute of an indicator when available, or else as regular attributes of the indicator. 
+
+Most metadata attributes are treated as read-only except for `default_pane` which can be modifed by some primitives/modifiers ...
+
+
+
+## Retrieve metadata with `get_info`
+
+```python
+from mplchart.utils import get_info
+
+default_pane = get_info(indicator, 'default_pane')
+```
+
+## Known attributes
+
+```python
+same_scale: bool        # wether the output uses same scale as input
+defaul_pane: str        # wich pane to use for a new scale
+overbought: float       # overbought level
+oversold: float         # oversold level
+yticks: tuple           # force major ticks
+```
+
+## Design Questions 
+
+- Should we split main attributes like `same_scale`, `default_pane` from the other optional read-only attibutes ?
+- Should we have a `force_pane` uopdatable attribute to override `default_pane` read-only attribute. Main logic is in the `Chart.get_axes` method.

pyproject.toml

@@ -19,7 +19,7 @@ classifiers = [
 ]
 
 [dependency-groups]
-dev = ["numpy<2.0.0", "yfinance", "pytest", "nbmake", "ipykernel", "ta-lib", "ruff"]
+dev = ["numpy<2.0.0", "yfinance", "ta-lib", "pytest", "nbmake", "ipykernel", "jinja2", "ipywidgets", "ruff"]
 
 
 [tool.hatch.build]

src/mplchart/chart.py

@@ -11,7 +11,7 @@
 
 from .wrappers import get_wrapper
 from .colors import closest_color
-from .utils import series_xy, same_scale
+from .utils import series_xy, same_scale, get_info
 from .layout import make_twinx, StandardLayout
 from .mapper import RawDateMapper, DateIndexMapper
 
@@ -297,7 +297,7 @@ def get_target(self, indicator):
         if indicator is None:
             return "same"
 
-        default_pane = getattr(indicator, "default_pane", None)
+        default_pane = get_info(indicator, "default_pane", None)
         if default_pane is not None:
             return default_pane
 
@@ -433,7 +433,7 @@ def plot_indicator(self, data, indicator):
             indicator = wrapper
 
         # Select axes according to indicator properties (default_pane, same_scale)
-        # target = self.default_pane(indicator)
+        # target = self.get_target(indicator)
         # ax = self.get_axes(target)
         ax = None
 

src/mplchart/utils.py

@@ -7,14 +7,27 @@
 TALIB_SAME_SCALE = "Output scale same as input"
 
 
+
+def get_info(indicator, name: str, default=None):
+    """get indicator info"""
+
+    if hasattr(indicator, "info"):  # talib
+        info = indicator.info
+    else:
+        info = vars(indicator)
+
+    return info.get(name, default)
+
+
+
 def same_scale(indicator):
     """Whether indicator uses the same scale as inputs"""
 
     if hasattr(indicator, "function_flags"):  # talib
         flags = indicator.function_flags or ()
         return TALIB_SAME_SCALE in flags
 
-    return getattr(indicator, "same_scale", False)
+    return get_info(indicator, "same_scale", False)
 
 
 def get_name(indicator):

src/mplchart/wrappers.py

@@ -7,7 +7,7 @@
 from functools import singledispatch
 
 from .model import Wrapper
-from .utils import get_name, get_label
+from .utils import get_name, get_label, get_info
 
 
 @singledispatch
@@ -107,12 +107,12 @@ def plot_result(self, data, chart, ax=None):
             )
             counter += 1
 
-        yticks = getattr(self.indicator, "yticks", ())
+        yticks = get_info(self.indicator, "yticks", ())
         if yticks:
             ax.set_yticks(yticks)
             ax.grid(axis="y", which="major", linestyle="-", linewidth=2)
 
-        oversold = getattr(self.indicator, "oversold", None)
+        oversold = get_info(self.indicator, "oversold", None)
         if oversold is not None:
             color = chart.get_color("oversold", ax, self.indicator, fallback="fill")
             with np.errstate(invalid="ignore"):
@@ -126,7 +126,7 @@ def plot_result(self, data, chart, ax=None):
                     alpha=0.5,
                 )
 
-        overbought = getattr(self.indicator, "overbought", None)
+        overbought = get_info(self.indicator, "overbought", None)
         if overbought is not None:
             color = chart.get_color("overbought", ax, self.indicator, fallback="fill")
             with np.errstate(invalid="ignore"):