[Python-Dev] Adding support to curses library

[Heracles]

Hello,

I am working on a patch to add to the _cursesmodule.c file of the Python
core libraries.  I figured I would take on one of the implemented functions
to try to get my feet wet contributing to the project.  At any rate, I have
the following function defined in the 2.7.a version updated from SVN this
morning:

------------- Snippet ---------------------------
// Insert new method color_set Steve Owens 2/24/2009
//   The curses library color_set function has the following signature:
//       int color_set(short color_pair_number, void* opts); 
static PyObject *
PyCurses_color_set(PyObject *self, PyObject *args)
{
   short color_pair_number;
   void * opts;
   int erg;

   // These macros ought to be documented in the API docs
   // but they aren't yet.
   PyCursesInitialised
   PyCursesInitialisedColor

   // Per ncurses Man Page: 
   //   The routine color_set sets the current color of the given window to
   // the foreground/background combination described by the
color_pair_number. 
   // The parameter opts is reserved for future use, applications must
supply a 
   // null pointer. 
   switch(PyTuple_Size(args))
   {
   case 1:
	   // Dont make them pass a useless null pointer.
	   if (!PyArg_ParseTuple(args, "h", &color_pair_number)) return NULL;
	   break;
   case 2:
	   // Allow them to pass the opts pointer so that when ncurses is later
updated.
	   // This method will still work.
	   if (!PyArg_ParseTuple(args, "hO&", &color_pair_number, &opts)) return
NULL;	
	   break;
   default:
      PyErr_SetString(PyExc_TypeError, "color_set requires 1 or 2 arguments
(color_pair_number[, opts]?)");
	  return NULL;
   }

   erg = color_set(color_pair_number, opts); // Debating on forcing null
here.
   
   if (erg == ERR) 
	  return PyCursesCheckERR(erg, "color_set");
   else
      PyInt_FromLong((long) 1L); 
}
-------------End  Snippet ---------------------------

I also have the following added in (see last line of the snippet):

------------- Snippet ---------------------------
static PyMethodDef PyCurses_methods[] = {
  {"baudrate",            (PyCFunction)PyCurses_baudrate, METH_NOARGS},
  {"beep",                (PyCFunction)PyCurses_beep, METH_NOARGS},
  {"can_change_color",    (PyCFunction)PyCurses_can_change_color,
METH_NOARGS},
  {"cbreak",              (PyCFunction)PyCurses_cbreak, METH_VARARGS},
  {"color_content",       (PyCFunction)PyCurses_Color_Content,
METH_VARARGS},
  {"color_pair",          (PyCFunction)PyCurses_color_pair, METH_VARARGS},
  {"color_set",           (PyCFunction)PyCurses_color_set, METH_VARARGS},
-------------End  Snippet ---------------------------

The code compiles and installs fine, but when I run the following unit test,
I get a segmentation fault:

------------- Snippet ---------------------------
import unittest, curses
from test import test_support

def testCursesColorSet(stdscrn):
   curses.init_pair(1, curses.COLOR_RED, curses.COLOR_WHITE)
   curses.init_pair(2, curses.COLOR_WHITE, curses.COLOR_BLUE);
   i = curses.color_set(1, NULL);
   stdscrn.addstr("RED/BLACK (%0)\n".format(i))
   i = curses.color_set(2, NULL);
   stdscrn.print("WHITE/BLUE (%0)\n".format(i))
   i = curses.color_set(0, NULL);
   stdscrn.print("Default (%0)\n".format(i))


def test_main(stdscrn):
   curses.savetty()
   if curses.has_color():
      testCursesColorSet(stdscrn)
   else
      stdscr.addstr( "Test Aborted: Color not supported on this terminal.")


if __name__ == '__main__':
    curses.wrapper(test_main)
-------------End  Snippet ---------------------------

It turns out that by commenting out this line in the _cursesmodule.c code,
allows the unit test to run 
obviously reporting the error as expected:

------------- Snippet ---------------------------
//erg = color_set(color_pair_number, opts); // Debating on forcing null
here.
-------------End  Snippet ---------------------------

At any rate I am stuck.  I am still trying to build just a plain C file
which will test the color_set function 
outside of python, but that is another task.

Any suggestions?


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