Finally fixing that pesky comma (#212)

Author: henryiii

include/boost/histogram/python/kwargs.hpp

@@ -39,10 +39,7 @@ T optional_arg(py::kwargs &kwargs, const char *name, T original_value) {
 /// Run this last; it will provide an error if other keyword are still present
 inline void finalize_args(const py::kwargs &kwargs) {
     if(kwargs.size() > 0) {
-        std::stringstream out;
-        for(const auto &item : kwargs) {
-            out << ", " << item.first;
-        }
-        throw py::key_error("Unidentfied keywords found:" + out.str());
+        auto keys = py::str(", ").attr("join")(kwargs.attr("keys")());
+        throw py::key_error(py::str("Unidentified keywords found: {0}").format(keys));
     }
 }

tests/test_public_hist.py

@@ -66,6 +66,9 @@ def test_fill_int_1d():
         h.fill()
     with pytest.raises(ValueError):
         h.fill(1, 2)
+    with pytest.raises(KeyError) as k:
+        h.fill(1, fiddlesticks=2)
+    assert k.value.args[0] == "Unidentified keywords found: fiddlesticks"
 
     h.fill(-3)
     assert h.empty()