python: convert std::system_error to IOError or derived exceptions (#119

)
project-gemmi · May 24, 2021 · 6ee7016 · 6ee7016
1 parent 3dab16b
commit 6ee7016
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diff --git a/python/gemmi.cpp b/python/gemmi.cpp
@@ -80,6 +80,17 @@ PYBIND11_MODULE(gemmi, mg) {
   mg.doc() = "Python bindings to GEMMI - a library used in macromolecular\n"
              "crystallography and related fields";
   mg.attr("__version__") = GEMMI_VERSION;
+
+  py::register_exception_translator([](std::exception_ptr p) {
+    try {
+      if (p)
+        std::rethrow_exception(p);
+    } catch (const std::system_error &e) {
+      const int errornum = e.code().value();
+      PyErr_SetObject(PyExc_IOError, py::make_tuple(errornum, e.what()).ptr());
+    }
+  });
+
   py::module cif = mg.def_submodule("cif", "CIF file format");
   add_cif(cif);
   add_symmetry(mg);

diff --git a/tests/test_cif.py b/tests/test_cif.py
@@ -239,6 +239,10 @@ def test_reading_gzipped_file(self):
         self.assertEqual(len(nonexistent), 0)
         self.assertEqual(nonexistent.width(), 0)
 
+    def test_file_not_found(self):
+        with self.assertRaises(IOError):
+            cif.read('file-that-does-not-exist.cif')
+
     def test_line_endings(self):
         lines = ['data_a', '_a_field', ';', 'text line', '2nd line', ';']
         for eol in ('\r\n', '\n'):