Remove python_compat.h (#417)

We don't need compatibility with older Python, so we can
simplify the code and just move it into the C++ file where
it is used.

Signed-off-by: Chris Lalancette <[email protected]>

Author: clalancette

tf2_py/CMakeLists.txt

@@ -36,8 +36,6 @@ endif()
 
 ament_python_install_package(${PROJECT_NAME})
 
-include_directories(include)
-
 function(set_properties _targetname _build_type)
   set_target_properties(${_targetname} PROPERTIES
     PREFIX ""

tf2_py/include/python_compat.h

@@ -1,4 +1,3 @@
-#include <python_compat.h>
 #include <Python.h>
 
 #include <tf2/buffer_core.h>
@@ -7,6 +6,53 @@
 #include <string>
 #include <vector>
 
+/// \brief Converts a C++ string into a Python string.
+/// \note The caller is responsible for decref'ing the returned object.
+/// \note If the return value is NULL then an exception is set.
+/// \return a new PyObject reference, or NULL
+inline PyObject * stringToPython(const std::string & input)
+{
+  return PyUnicode_FromStringAndSize(input.c_str(), input.size());
+}
+
+/// \brief Converts a C string into a Python string.
+/// \note The caller is responsible for decref'ing the returned object.
+/// \note If the return value is NULL then an exception is set.
+/// \return a new PyObject reference, or NULL
+inline PyObject * stringToPython(const char * input)
+{
+  return PyUnicode_FromString(input);
+}
+
+/// \brief Converts a Python string into a C++ string.
+/// \note The input PyObject is borrowed, and will not be decref'd.
+/// \note It's possible for this function to set an exception.
+///   If the returned string is empty, callers should check if an exception was
+///   set using PyErr_Ocurred().
+/// \return a new std::string instance
+inline std::string stringFromPython(PyObject * input)
+{
+  Py_ssize_t size;
+  const char * data;
+  data = PyUnicode_AsUTF8AndSize(input, &size);
+  return std::string(data, size);
+}
+
+/// \brief Imports a python module by name.
+/// \note The caller is responsible for decref'ing the returned object.
+/// \note If the return value is NULL then an exception is set.
+/// \return a reference to the imported module.
+inline PyObject * pythonImport(const std::string & name)
+{
+  PyObject * py_name = stringToPython(name);
+  if (!py_name) {
+    return nullptr;
+  }
+  PyObject * module = PyImport_Import(py_name);
+  Py_XDECREF(py_name);
+  return module;
+}
+
 // Run x (a tf method, catching TF's exceptions and reraising them as Python exceptions)
 //
 #define WRAP(x) \