Implemented get_macros

bob/core/__init__.py

@@ -15,5 +15,28 @@ def get_config():
   return bob.extension.get_config(__name__, version.externals, version.api)
 
 
+def get_macros():
+  """get_macros() -> macros
+
+  Returns a list of preprocessor macros, such as ``[(HAVE_BOOST, 1), (BOOST_VERSION,xx)]``.
+  This function is automatically used by :py:func:`bob.extension.get_bob_libraries` to retrieve the prerpocessor definitions that are required to use the C bindings of this library in dependent classes.
+  You shouldn't normally need to call this function by hand.
+
+  **Returns:**
+
+  ``macros`` : [str]
+    The list of preprocessor macros required to use the C bindings of this class.
+  """
+  # try to use pkg_config first
+  from bob.extension.boost import boost
+  macros = []
+  try:
+    b = boost()
+    macros = b.macros()
+  except:
+    pass
+  return macros
+
+
 # gets sphinx autodoc done right - don't remove it
 __all__ = [_ for _ in dir() if not _.startswith('_')]