clarify the empty variable name issue ([Bug 549285])

3 files changed, 71 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 2a09525..7b90e33 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2002-06-03  Miguel Sofer  <msofer@users.sourceforge.net>
+
+	* doc/Tcl.n: clarify the empty variable name issue ([Bug 549285]
+	reported by Tom Krehbiel, patch by Don Porter).
+
 2002-05-31  Don Porter  <dgp@users.sourceforge.net>
 
 	* library/package.tcl:  Fixed leak of slave interp in [pkg_mkIndex].
diff --git a/doc/Tcl.n b/doc/Tcl.n
index 6bd8511..4ad1b63 100644
--- a/doc/Tcl.n
+++ b/doc/Tcl.n
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: Tcl.n,v 1.3 1999/04/16 00:46:33 stanton Exp $
+'\" RCS: @(#) $Id: Tcl.n,v 1.4 2002/06/03 16:31:24 msofer Exp $
 '\"
 .so man.macros
 .TH Tcl n "8.1" Tcl "Tcl Built-In Commands"
@@ -82,13 +82,14 @@ Variable substitution may take any of the following forms:
 .RS
 .TP 15
 \fB$\fIname\fR
-\fIName\fR is the name of a scalar variable;  the name is terminated
-by any character that isn't a letter, digit, or underscore.
+\fIName\fR is the name of a scalar variable;  the name is a sequence
+of one or more characters that are a letter, digit, or underscore.
 .TP 15
 \fB$\fIname\fB(\fIindex\fB)\fR
 \fIName\fR gives the name of an array variable and \fIindex\fR gives
 the name of an element within that array.
-\fIName\fR must contain only letters, digits, and underscores.
+\fIName\fR must contain only letters, digits, and underscores,
+but may be an empty string.
 Command substitutions, variable substitutions, and backslash
 substitutions are performed on the characters of \fIindex\fR.
 .TP 15
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index e9ebbd4..2374cd3 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclExecute.c,v 1.57 2002/05/31 22:20:19 dgp Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.58 2002/06/03 16:31:25 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -66,6 +66,33 @@ TCL_DECLARE_MUTEX(execMutex)
 int tclTraceExec = 0;
 #endif
 
+typedef struct ThreadSpecificData {
+    /*
+     * The following global variable is use to signal matherr that Tcl
+     * is responsible for the arithmetic, so errors can be handled in a
+     * fashion appropriate for Tcl.  Zero means no Tcl math is in
+     * progress;  non-zero means Tcl is doing math.
+     */
+    
+    int mathInProgress;
+
+} ThreadSpecificData;
+
+static Tcl_ThreadDataKey dataKey;
+
+/*
+ * The variable below serves no useful purpose except to generate
+ * a reference to matherr, so that the Tcl version of matherr is
+ * linked in rather than the system version. Without this reference
+ * the need for matherr won't be discovered during linking until after
+ * libtcl.a has been processed, so Tcl's version won't be used.
+ */
+
+#ifdef NEED_MATHERR
+extern int matherr();
+int (*tclMatherrPtr)() = matherr;
+#endif
+
 /*
  * Mapping from expression instruction opcodes to strings; used for error
  * messages. Note that these entries must match the order and number of the
@@ -3912,6 +3939,7 @@ TclExecuteByteCode(interp, codePtr)
 		 */
 
 		BuiltinFunc *mathFuncPtr;
+		ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
 		if ((opnd < 0) || (opnd > LAST_BUILTIN_FUNC)) {
 		    TRACE(("UNRECOGNIZED BUILTIN FUNC CODE %d\n", opnd));
@@ -3919,8 +3947,10 @@ TclExecuteByteCode(interp, codePtr)
 		}
 		mathFuncPtr = &(builtinFuncTable[opnd]);
 		DECACHE_STACK_INFO();
+		tsdPtr->mathInProgress++;
 		result = (*mathFuncPtr->proc)(interp, eePtr,
 		        mathFuncPtr->clientData);
+		tsdPtr->mathInProgress--;
 		CACHE_STACK_INFO();
 		if (result != TCL_OK) {
 		    goto checkForCatch;
@@ -3941,10 +3971,13 @@ TclExecuteByteCode(interp, codePtr)
 				    * is the 0-th argument. */
 		Tcl_Obj **objv;	   /* The array of arguments. The function
 				    * name is objv[0]. */
+		ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
 		objv = &(stackPtr[stackTop - (objc-1)]); /* "objv[0]" */
 		DECACHE_STACK_INFO();
+		tsdPtr->mathInProgress++;
 		result = ExprCallMathFunc(interp, eePtr, objc, objv);
+		tsdPtr->mathInProgress--;
 		CACHE_STACK_INFO();
 		if (result != TCL_OK) {
 		    goto checkForCatch;
@@ -5645,6 +5678,7 @@ ExprCallMathFunc(interp, eePtr, objc, objv)
     long i;
     double d;
     int j, k, result;
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
     Tcl_ResetResult(interp);
 
@@ -5742,8 +5776,10 @@ ExprCallMathFunc(interp, eePtr, objc, objv)
      * Invoke the function and copy its result back into valuePtr.
      */
 
+    tsdPtr->mathInProgress++;
     result = (*mathFuncPtr->proc)(mathFuncPtr->clientData, interp, args,
 	    &funcResult);
+    tsdPtr->mathInProgress--;
     if (result != TCL_OK) {
 	goto done;
     }
@@ -5833,6 +5869,30 @@ TclExprFloatError(interp, value)
     }
 }
 
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclMathInProgress --
+ *
+ *	This procedure is called to find out if Tcl is doing math
+ *	in this thread.
+ *
+ * Results:
+ *	0 or 1.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclMathInProgress()
+{
+    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+    return tsdPtr->mathInProgress;
+}
+
 #ifdef TCL_COMPILE_STATS
 /*
  *----------------------------------------------------------------------