[Python-Dev] Adding support to curses library

[Ulrich Berning]

Heracles wrote:

>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?
>
>
>  
>
As long as Python is written in C, please don't use C++ comments, some C 
compilers don't like them.

Ulli