fix #365 - added a regression test and a fix based on pull request #393

Author: astanin

tabulate/__init__.py

@@ -2288,7 +2288,7 @@ def tabulate(
         )
 
     if maxheadercolwidths is not None:
-        num_cols = len(list_of_lists[0])
+        num_cols = len(list_of_lists[0]) if list_of_lists else len(headers)
         if isinstance(maxheadercolwidths, int):  # Expand scalar for all columns
             maxheadercolwidths = _expand_iterable(
                 maxheadercolwidths, num_cols, maxheadercolwidths

test/test_regression.py

@@ -548,3 +548,15 @@ def test_empty_table_with_colalign():
         ]
     )
     assert_equal(expected, table)
+
+
+def test_empty_table_with_maxheadercolwidths():
+    "Regression: empty table with maxheadercolwidths kwarg (issue #365)"
+    result = tabulate([], headers=["one", "two", "three"], maxheadercolwidths=5)
+    expected = "\n".join(
+        [
+            "one    two    three",
+            "-----  -----  -------",
+        ]
+    )
+    assert_equal(expected, result)