perf: Postpone bokeh.models import

geoviews/element/geo.py

@@ -1,6 +1,7 @@
+import sys
+
 import numpy as np
 import param
-from bokeh.models import MercatorTileSource
 from cartopy import crs as ccrs
 from cartopy.feature import Feature as cFeature
 from cartopy.io.img_tiles import GoogleTiles
@@ -80,6 +81,12 @@ class HvImageStack: ...
 
 geographic_types = (GoogleTiles, cFeature, BaseGeometry)
 
+def _check_bokeh_mercator(data) -> bool:
+    if "bokeh.models" in sys.modules:
+        from bokeh.models import MercatorTileSource
+        return isinstance(data, MercatorTileSource)
+    return False
+
 def is_geographic(element, kdims=None):
     """
     Utility to determine whether the supplied element optionally
@@ -267,8 +274,7 @@ class WMTS(_GeoFeature):
     layer = param.String(doc="The layer on the tile service")
 
     def __init__(self, data, kdims=None, vdims=None, **params):
-        if ((MercatorTileSource and isinstance(data, MercatorTileSource)) or
-            (GoogleTiles and isinstance(data, GoogleTiles))):
+        if _check_bokeh_mercator(data) or isinstance(data, GoogleTiles):
             data = data.url
         elif WebMapTileService and isinstance(data, WebMapTileService):
             pass

geoviews/tests/test_import.py

@@ -8,7 +8,7 @@ def test_no_blocklist_imports():
     import sys
     import geoviews as gv
 
-    blocklist = {"panel", "IPython", "datashader", "iris", "dask"}
+    blocklist = {"panel", "IPython", "datashader", "iris", "dask", "bokeh.models"}
     mods = blocklist & set(sys.modules)
 
     if mods: