Hack to get show_ast() running with Python 3.12

notebooks/shared/bookutils/__init__.py

@@ -158,14 +158,44 @@ def getsourcelines(function: Any) -> Tuple[List[str], int]:
 
 # Showing ASTs
 def show_ast(tree: AST) -> Optional[Any]:
-    if rich_output():
-        import showast  # We can import showast only when in a notebook
-        return showast.show_ast(tree)
-    else:
+    if not rich_output():
+        # We can import showast only when in a notebook
         import ast  # Textual alternative
         print(ast.dump(tree))
         return None
 
+    # show_ast() no longer works in Python 3.12: the `imp` module is deprecated
+    # import showast
+    # return showast.show_ast(tree)
+
+    # Workaround, avoiding `imp`
+    import_showast()
+    import showast
+    from showast.rendering.graphviz import render
+    return render(tree, showast.Settings)
+
+# Allow importing the showast module
+def import_showast():
+    try:
+        import showast
+        return
+    except ModuleNotFoundError:
+        pass
+
+    # Create a local (empty) 'imp' module while importing showast
+    # This is an ugly hack until the `showast` module is updated to 3.12
+    import os, sys, shutil
+    os.mkdir('imp')
+    imp_init = os.path.join('imp', '__init__.py')
+    with open(imp_init, 'w') as fd:
+        pass
+    original_sys_path = sys.path
+    sys.path = ['.'] + sys.path
+    import showast
+    sys.path = original_sys_path
+    shutil.rmtree('imp')
+
+
 # Escaping unicode characters into ASCII for user-facing strings
 def unicode_escape(s: str, error: str = 'backslashreplace') -> str:
     def ascii_chr(byte: int) -> str: