Q43436: Accessing Predefined Switches in C-Extension

Article: Q43436
Product(s): See article
Version(s): 1.02   |  1.02
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | FindSwitch | mspl13_basic
Last Modified: 17-MAY-1989

When writing a C extension for Microsoft Editor Version 1.02, you can
access the predefined editor switches through the function
FindSwitch(). FindSwitch() is intended to be used to access the values
of the predefined editor switches, not to modify the values. Modifying
the switches through FindSwitch() has undefined results.

The following code fragment retrieves the value of the switch
"tabstops" for use in your C extension:

#include "ext.h"
      .
      .
      .

PSWI pTabStops ;
int  nTabStops ;
      .
      .
      .

pTabStops = FindSwitch ("tabstops") ;
nTabStops = *(pTabStops->act.ival) ;

Any change to the value of the switch "tabstops" made outside your
C extension will be reflected in the value of nTabStops inside your
C extension.

You can find the FindSwitch() prototype in the include file EXT.H. The
function FindSwitch() is not available in the Microsoft Editor Version
1.00.

The structure, swiTable, consists of a series of structures, each
structure describing a user-defined switch. The purpose of swiTable is
to add user-defined, not predefined, switches. It is incorrect to name
the predefined switches in the switch table. For that reason the
following example is incorrect as it names "tabstops," a predefined
switch:

struct swiDesc swiTable [] =
 {
  {"tabstops", &nTabStops, NUMERIC | RADIX10}   /*  INCORRECT  */
  { NULL, NULL, 0}
 } ;

Do not modify the predefined switches through the switch table. You
can change the values of the predefined switches from within an
editing session or in TOOLS.INI.

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