Delegate external axes methods with guardrails (#514)

* Delegate external axes methods with guardrails

Route attribute access to external axes by default while keeping UltraPlot-specific formatting and container overrides on the parent.

* Simplify external axes delegation

Delegate missing methods to the external axes via __getattr__ and keep a small blocklist for UltraPlot formatting/guide APIs.

Author: cvanelteren

ultraplot/axes/container.py

@@ -61,6 +61,14 @@ class ExternalAxesContainer(CartesianAxes):
     ``external_padding=2`` or ``external_padding=0`` to disable padding entirely.
     """
 
+    _EXTERNAL_DELEGATE_BLOCKLIST = {
+        # Keep UltraPlot formatting/guide behaviors on the container.
+        "format",
+        "colorbar",
+        "legend",
+        "set_title",
+    }
+
     def __init__(
         self, *args, external_axes_class=None, external_axes_kwargs=None, **kwargs
     ):
@@ -799,28 +807,14 @@ def get_tightbbox(self, renderer, *args, **kwargs):
 
     def __getattr__(self, name):
         """
-        Delegate attribute access to the external axes when not found on container.
-
-        This allows the container to act as a transparent wrapper, forwarding
-        plotting methods and other attributes to the external axes.
+        Delegate missing attributes to the external axes unless blocked.
         """
-        # Avoid infinite recursion for private attributes
-        # But allow parent class lookups during initialization
-        if name.startswith("_"):
-            # During initialization, let parent class handle private attributes
-            # This prevents interfering with parent class setup
+        if name in self._EXTERNAL_DELEGATE_BLOCKLIST:
             raise AttributeError(
                 f"'{type(self).__name__}' object has no attribute '{name}'"
             )
-
-        # Try to get from external axes if it exists
-        if hasattr(self, "_external_axes") and self._external_axes is not None:
-            try:
-                return getattr(self._external_axes, name)
-            except AttributeError:
-                pass
-
-        # Not found anywhere
+        if self._external_axes is not None:
+            return getattr(self._external_axes, name)
         raise AttributeError(
             f"'{type(self).__name__}' object has no attribute '{name}'"
         )