@paroj Thanks for contribution to OpenCV project. Could you add test for Python to check that string reported in bindings is not empty at least. It helps to check regressions with CI in automated way.

This patch should go into 3.4 branch first. We will merge changes from 3.4 into master regularly (weekly/bi-weekly).

So, please:

• change "base" branch of this PR: master => 3.4 (use "Edit" button near PR title)
• rebase your commits from master onto 3.4 branch. For example:
  git rebase -i --onto upstream/3.4 upstream/master
  (check list of your commits, save and quit (Esc + "wq" + Enter)
  where upstream is configured by following this GitHub guide and fetched (git fetch upstream).
• push rebased commits into source branch of your fork (with --force option)

Note: no need to re-open PR, apply changes "inplace".

string reported in bindings is not empty at least

Actually, It can be empty on some platforms or build configurations.

This patch should go into 3.4 branch first. We will merge changes from 3.4 into master regularly (weekly/bi-weekly).

bindings generator in 3.4 does not seem to cope with std::string type, changed back to master

bindings generator in 3.4 does not seem to cope with std::string type

Please add this to cv2.cpp:

 template<>
 PyObject* pyopencv_from(const String& value)
 {
     return PyString_FromString(value.empty() ? "" : value.c_str());
 }
+
+#if CV_VERSION_MAJOR == 3
+template<>
+PyObject* pyopencv_from(const std::string& value)
+{
+    return PyString_FromString(value.empty() ? "" : value.c_str());
+}
+#endif