Backport of TIP #440.

doc/tclvars.n

@@ -254,6 +254,11 @@ so extension writers can specify which package to load depending on the
 C run-time library that is in use.  This is not an indication that this core
 contains symbols.
 .TP
+\fBengine\fR
+.
+The name of the Tcl language implementation.  When the interpreter is first
+created, this is always set to the string \fBTcl\fR.
+.TP
 \fBmachine\fR
 The instruction set executed by this machine, such as
 \fBintel\fR, \fBPPC\fR, \fB68k\fR, or \fBsun4m\fR.  On UNIX machines, this

generic/tclBasic.c

@@ -789,6 +789,13 @@ Tcl_CreateInterp(void)
 
     TclInitEmbeddedConfigurationInformation(interp);
 
+    /*
+     * TIP #440: Declare the name of the script engine to be "Tcl".
+     */
+
+    Tcl_SetVar2(interp, "tcl_platform", "engine", "Tcl",
+	    TCL_GLOBAL_ONLY);
+
     /*
      * Compute the byte order of this machine.
      */

tests/platform.test

@@ -20,6 +20,10 @@ namespace eval ::tcl::test::platform {
 
 testConstraint testCPUID [llength [info commands testcpuid]]
 
+test platform-1.0 {tcl_platform(engine)} {
+  set tcl_platform(engine)
+} {Tcl}
+
 test platform-1.1 {TclpSetVariables: tcl_platform} {
     interp create i
     i eval {catch {unset tcl_platform(debug)}}
@@ -27,7 +31,7 @@ test platform-1.1 {TclpSetVariables: tcl_platform} {
     set result [i eval {lsort [array names tcl_platform]}]
     interp delete i
     set result
-} {byteOrder machine os osVersion platform pointerSize user wordSize}
+} {byteOrder engine machine os osVersion platform pointerSize user wordSize}
 
 # Test assumes twos-complement arithmetic, which is true of virtually
 # everything these days.  Note that this does *not* use wide(), and

tests/safe.test

@@ -166,7 +166,7 @@ test safe-6.3 {test safe interpreters knowledge of the world} {
 	set r [lreplace $r $threaded $threaded]
     }
     set r
-} {byteOrder platform pointerSize wordSize}
+} {byteOrder engine platform pointerSize wordSize}
 
 # more test should be added to check that hostname, nameofexecutable,
 # aren't leaking infos, but they still do...