Add python bindings for the reader and writer by reusing the current

Reader and Writer

python/podio/frame.py

@@ -104,7 +104,10 @@ def __init__(self, data=None):
     """
     # Explicitly check for None here, to not return empty Frames on nullptr data
     if data is not None:
-      self._frame = podio.Frame(data)
+      if isinstance(data, cppyy.gbl.podio.Frame):
+        self._frame = data
+      else:
+        self._frame = podio.Frame(data)
     else:
       self._frame = podio.Frame()
 

python/podio/frame_iterator.py

@@ -4,6 +4,7 @@
 # pylint: disable-next=import-error # gbl is a dynamic module from cppyy
 from cppyy.gbl import std
 from podio.frame import Frame
+import cppyy
 
 
 class FrameCategoryIterator:
@@ -27,7 +28,12 @@ def __iter__(self):
 
   def __next__(self):
     """Get the next available Frame or stop."""
-    frame_data = self._reader.readNextEntry(self._category)
+    try:
+      frame_data = self._reader.readNextFrame(self._category)
+    except AttributeError:
+      frame_data = self._reader.readNextEntry(self._category)
+    except std.runtime_error:
+      raise StopIteration
     if frame_data:
       return Frame(std.move(frame_data))
 
@@ -52,14 +58,22 @@ def __getitem__(self, entry):
       raise IndexError
 
     try:
+      frame_data = self._reader.readFrame(self._category, entry)
+    except AttributeError:
       frame_data = self._reader.readEntry(self._category, entry)
     except std.bad_function_call:
       print('Error: Unable to read an entry of the input file. This can happen when the '
             'ROOT model dictionaries are not in LD_LIBRARY_PATH. Make sure that LD_LIBRARY_PATH '
             'points to the library folder of the installation of podio and also to the library '
             'folder with your data model\n')
       raise
+    except std.runtime_error:
+      raise IndexError('Unable to read frame, you might be trying to read beyond bounds or a '
+                       'non-existent category')
+
     if frame_data:
-      return Frame(std.move(frame_data))
+      if isinstance(frame_data, cppyy.gbl.podio.ROOTFrameData):
+        return Frame(std.move(frame_data))
+      return Frame(frame_data)
 
     raise IndexError

python/podio/root_io.py

@@ -1,8 +1,9 @@
 #!/usr/bin/env python3
 """Python module for reading root files containing podio Frames"""
 
-from ROOT import gSystem
+from ROOT import gSystem, gInterpreter
 gSystem.Load('libpodioRootIO')  # noqa: E402
+gInterpreter.LoadFile("podio/Reader.h") # noqa: E402
 from ROOT import podio  # noqa: E402 # pylint: disable=wrong-import-position
 
 from podio.base_reader import BaseReaderMixin  # pylint: disable=wrong-import-position
@@ -12,6 +13,22 @@
 class Reader(BaseReaderMixin):
   """Reader class for reading podio root files."""
 
+  def __init__(self, filenames):
+    """Create a reader that reads from the passed file(s).
+
+    Args:
+        filenames (str or list[str]): file(s) to open and read data from
+    """
+    if isinstance(filenames, str):
+      filenames = (filenames,)
+
+    self._reader = podio.makeReader(filenames)
+
+    super().__init__()
+
+class ROOTFrameReader(BaseReaderMixin):
+  """Reader class for reading podio root files."""
+
   def __init__(self, filenames):
     """Create a reader that reads from the passed file(s).
 
@@ -69,6 +86,17 @@ def __init__(self, filenames):
 
 
 class Writer(BaseWriterMixin):
+  """Writer class for writing podio root files"""
+  def __init__(self, filename):
+    """Create a writer for writing files
+
+    Args:
+        filename (str): The name of the output file
+    """
+    self._writer = podio.makeWriter(filename)
+    super().__init__()
+
+class ROOTFrameWriter(BaseWriterMixin):
   """Writer class for writing podio root files"""
   def __init__(self, filename):
     """Create a writer for writing files