Defer ipython import (#255)

box/box.py

@@ -18,12 +18,6 @@
 except ImportError:
     from collections.abc import Callable, Iterable, Mapping
 
-try:
-    from IPython import get_ipython
-except ImportError:
-    ipython = False
-else:
-    ipython = True if get_ipython() else False
 
 import box
 from box.converters import (
@@ -56,6 +50,17 @@
 NO_NAMESPACE = object()
 
 
+def _is_ipython():
+    try:
+        from IPython import get_ipython
+    except ImportError:
+        ipython = False
+    else:
+        ipython = True if get_ipython() else False
+
+    return ipython
+
+
 def _exception_cause(e):
     """
     Unwrap BoxKeyError and BoxValueError errors to their cause.
@@ -483,7 +488,7 @@ def __setstate__(self, state):
         self.__dict__.update(state)
 
     def __get_default(self, item, attr=False):
-        if ipython and item in ("getdoc", "shape"):
+        if item in ("getdoc", "shape") and _is_ipython():
             return None
         default_value = self._box_config["default_box_attr"]
         if default_value in (self._box_config["box_class"], dict):