Remove internal py::DataWindow class (#1529)

- Internal method `frame.internal.window(row0, row1, col0, col1)` is removed. Same result can be achieved via `frame[row0:row1, col0:col1].to_list()`;
- Removed class `py::DataWindow` which used to handle the `.window()` call. This class has been around since the very early days of datatable, and grew useless over time;
- The `DT[i, j]` call is able to handle different row indices without problems, resolving issue #1527.

Closes #1527

CHANGELOG.md

@@ -99,6 +99,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - `DT.replace()` now throws an error if called with 0 or 1 argument (#1525).
   Thanks to [Arno Candel][] for discovering this issue.
 
+- Fixed crash when viewing a frame obtained by resizing a 0-row frame (#1527).
+  Thanks to [Nishant Kalonia][] for reporting.
+
 
 ### Changed
 
@@ -828,6 +831,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 [jonathan mckinney]: https://github.com/pseudotensor
 [michael frasco]: https://github.com/mfrasco
 [michal raška]: https://github.com/michal-raska
+[nishant kalonia]: https://github.com/nkalonia1
 [oleksiy kononenko]: https://github.com/oleksiyskononenko
 [olivier]: https://github.com/goldentom42
 [pasha stetsenko]: https://github.com/st-pasha

c/datatablemodule.cc

@@ -22,7 +22,6 @@
 #include "py_column.h"
 #include "py_columnset.h"
 #include "py_datatable.h"
-#include "py_datawindow.h"
 #include "py_encodings.h"
 #include "py_groupby.h"
 #include "py_rowindex.h"
@@ -228,7 +227,6 @@ PyInit__datatable()
   try {
     // Initialize submodules
     if (!init_py_types(m)) return nullptr;
-    if (!pydatawindow::static_init(m)) return nullptr;
     if (!pycolumn::static_init(m)) return nullptr;
     if (!pycolumnset::static_init(m)) return nullptr;
     if (!pydatatable::static_init(m)) return nullptr;

c/py_datatable.cc

@@ -14,7 +14,6 @@
 #include "frame/py_frame.h"
 #include "py_column.h"
 #include "py_columnset.h"
-#include "py_datawindow.h"
 #include "py_groupby.h"
 #include "py_rowindex.h"
 #include "py_types.h"
@@ -190,20 +189,6 @@ void _clear_types(obj* self) {
 }
 
 
-PyObject* window(obj* self, PyObject* args) {
-  int64_t row0, row1, col0, col1;
-  if (!PyArg_ParseTuple(args, "llll", &row0, &row1, &col0, &col1))
-    return nullptr;
-
-  PyObject* dwtype = reinterpret_cast<PyObject*>(&pydatawindow::type);
-  PyObject* nargs = Py_BuildValue("Ollll", self, row0, row1, col0, col1);
-  PyObject* res = PyObject_CallObject(dwtype, nargs);
-  Py_XDECREF(nargs);
-
-  return res;
-}
-
-
 PyObject* to_scalar(obj* self, PyObject*) {
   DataTable* dt = self->ref;
   if (dt->ncols == 1 && dt->nrows == 1) {
@@ -623,7 +608,6 @@ static void dealloc(obj* self) {
 //==============================================================================
 
 static PyMethodDef datatable_methods[] = {
-  METHODv(window),
   METHOD0(to_scalar),
   METHOD0(check),
   METHODv(column),

c/py_datatable.h

@@ -91,11 +91,6 @@ DECLARE_GETTER(
 
 //---- Methods -----------------------------------------------------------------
 
-DECLARE_METHOD(
-  window,
-  "window(row0, row1, col0, col1)\n\n"
-  "Retrieve DataTable's data within a window")
-
 DECLARE_METHOD(
   to_scalar,
   "to_scalar()\n\n"