Track source filename for G3Frame objects that are read in using G3Re…

…ader

core/include/core/G3Frame.h

@@ -60,6 +60,9 @@ class G3Frame {
 
 	FrameType type;
 
+	// Source filename (if output from G3Reader)
+	std::string filename;
+
 	// Add and remove data from the frame. Note that retrieved data is
 	// const. Get<> is like operator [], except that it does a dynamic
 	// cast to a type for you.

core/src/G3Reader.cxx

@@ -104,6 +104,7 @@ void G3Reader::Process(G3FramePtr frame, std::deque<G3FramePtr> &out)
 	if (_save != nullptr)
 		PyEval_RestoreThread(_save);
 
+	frame->filename = cur_file_;
 	out.push_back(frame);
 	n_frames_read_++;
 }

core/src/python.cxx

@@ -459,6 +459,8 @@ BOOST_PYTHON_MODULE(core)
 	    .def("__init__", bp::make_constructor(g3frame_char_constructor, bp::default_call_policies(), bp::args("adhoctypecode")), "Create a frame with an ad-hoc (non-standard) type code. Use sparingly and with care.")
 	    .def_readwrite("type", &G3Frame::type, "Type code for frame. "
 	      "See general G3Frame docstring.")
+	    .def_readonly("filename", &G3Frame::filename, "Source filename for frame, "
+	      "if read in using G3Reader. This attribute is fragile, use at your own risk.")
 	    .def("__setitem__", &g3frame_python_put)
 	    .def("__getitem__", &g3frame_python_get)
 	    .def("keys", &g3frame_keys, "Returns a list of keys in the frame.")

doc/frames.rst

@@ -8,6 +8,8 @@ Frames have fast serialization to and from disk (see the G3Reader and G3Writer m
 
 Each frame has a type defined under the ``core.G3FrameType`` namespace. These are meant to indicate different types of data (calibration vs. scan data, for example) and, in general, many types of frames will be interleaved in the same data stream. A good general rule for whether data should be in a different frame type is to consider the rates at which the data change: data that change at the same speed (e.g. bolometer data and pointing) should share a frame, while data that change at different speeds (e.g. calibration constants and bolometer data) should be separated.
 
+Each frame also has a ``filename`` attribute, which is set when frames are read in using the ``core.G3Reader`` pipeline module. This attribute is not serialized with the frame, so will be an empty string when used with pickling or multiprocessing.
+
 A brief description of the intention of each frame type follows along with a table containing a representative minimal set of data likely to be contained by a frame of a given type. The list is neither exhaustive nor truly minimal: other data can and will be present and some of the data listed here may have been removed or renamed. Neither is this an exhaustive list of frame types: any single character code can be [ab]used as a frame type for special purpose tools.
 
 .. contents:: Contents

gcp/src/ARCFileReader.cxx

@@ -859,6 +859,7 @@ void ARCFileReader::Process(G3FramePtr frame, std::deque<G3FramePtr> &out)
 		outframe->Put(temp->first, templ);
 	}
 
+	outframe->filename = cur_file_;
 	out.push_back(outframe);
 
 	delete [] buffer;