Source Code 1992 March/Source_Code_CD-ROM_Walnut_Creek_March_1992.iso/usenet/altsrcs/0/0979/tcl.pat.vars

Internet Message Format | 1990-12-28 | 4.6 KB

From ficc%sugar!texbell!allspice.Berkeley.EDU!ouster Sat Mar  3 18:12:05 1990
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Date: Fri, 2 Mar 90 08:43:20 PST
From: [e-mail] (John Ousterhout)
Message-Id: <[e-mail]>
To: ficc![e-mail]
Subject: Re: Variables fix
Cc: [e-mail]
Status: O

I hope to have the non-existent-variable patches complete in the
next week or two.  In case that's not soon enough for you, I'm
returning a copy of your patches at the end of this message.
>From ficc![e-mail] Thu Feb 22 21:14:42 1990
From: ficc![e-mail]
To: [e-mail]
Subject: Patches for empty variables.
Cc: [e-mail]
Date: Wed Feb 21 16:29:46 1990

The following patches let you differentiate between empty variables
and non-existant ones.

*** old/tclBasic.c
--- tcl/tclBasic.c
***************
*** 686,692 ****
               */

              value = Tcl_ParseVar(interp, src, &tmp);
!             if (*value == 0) {
                  result = TCL_ERROR;
                  goto done;
              }
--- 686,692 ----
               */

              value = Tcl_ParseVar(interp, src, &tmp);
!             if (value == 0) {
                  result = TCL_ERROR;
                  goto done;
              }
***************
*** 1211,1216 ****
--- 1211,1217 ----
      char *buffer, *oldVar;

      oldVar = Tcl_GetVar(interp, "errorInfo", 1);
+     if(!oldVar) oldVar = "";
      length = strlen(oldVar);
      buffer = (char *)malloc((unsigned) (length + strlen(message) + 1));
      strcpy(buffer, oldVar);
*** old/tclExpr.c
--- tcl/tclExpr.c
***************
*** 250,256 ****
      case '$':
          infoPtr->token = NUMBER;
          var = Tcl_ParseVar(infoPtr->interp, p, &infoPtr->expr);
!         if (*var == '\0') {
          return TCL_ERROR;
          }
          if (((Interp *) infoPtr->interp)->noEval) {
--- 250,256 ----
      case '$':
          infoPtr->token = NUMBER;
          var = Tcl_ParseVar(infoPtr->interp, p, &infoPtr->expr);
!         if (var == 0) {
          return TCL_ERROR;
          }
          if (((Interp *) infoPtr->interp)->noEval) {
*** old/tclProc.c
--- tcl/tclProc.c
***************
*** 158,164 ****
   * Results:
   *    The return value points to the current value of varName.  If
   *    the variable is not defined in interp, either as a local or
!  *    global variable, then a pointer to an empty string is returned.
   *    Note:  the return value is only valid up until the next call to
   *    Tcl_SetVar;  if you depend on the value lasting longer than that,
   *    then make yourself a private copy.
--- 158,165 ----
   * Results:
   *    The return value points to the current value of varName.  If
   *    the variable is not defined in interp, either as a local or
!  *    global variable, then a NULL pointer is returned.
!  *
   *    Note:  the return value is only valid up until the next call to
   *    Tcl_SetVar;  if you depend on the value lasting longer than that,
   *    then make yourself a private copy.
***************
*** 185,191 ****
      varPtr = FindVar(&iPtr->varFramePtr->varPtr, varName);
      }
      if (varPtr == NULL) {
!     return "";
      }
      if (varPtr->flags & VAR_GLOBAL) {
      varPtr = varPtr->globalPtr;
--- 186,192 ----
      varPtr = FindVar(&iPtr->varFramePtr->varPtr, varName);
      }
      if (varPtr == NULL) {
!     return NULL;
      }
      if (varPtr->flags & VAR_GLOBAL) {
      varPtr = varPtr->globalPtr;
***************
*** 323,329 ****
      c = *string;
      *string = 0;
      result = Tcl_GetVar(interp, name, 0);
!     if (*result == '\0') {
      Tcl_Return(interp, (char *) NULL, TCL_STATIC);
      sprintf(interp->result, "couldn't find variable \"%.50s\"", name);
      }
--- 324,330 ----
      c = *string;
      *string = 0;
      result = Tcl_GetVar(interp, name, 0);
!     if (!result) {
      Tcl_Return(interp, (char *) NULL, TCL_STATIC);
      sprintf(interp->result, "couldn't find variable \"%.50s\"", name);
      }
***************
*** 360,366 ****
      char *value;

      value = Tcl_GetVar(interp, argv[1], 0);
!     if (*value == 0) {
          sprintf(interp->result, "couldn't find variable \"%.50s\"",
              argv[1]);
          return TCL_ERROR;
--- 361,367 ----
      char *value;

      value = Tcl_GetVar(interp, argv[1], 0);
!     if (value == 0) {
          sprintf(interp->result, "couldn't find variable \"%.50s\"",
              argv[1]);
          return TCL_ERROR;