Chapter 52. Tcl/Tk 8.1
Tcl/Tk 8.1 features Unicode support for Internationalization, thread safety, and a new regular expression package.
Tcl 8.1 should probably have been called Tcl 9.0. The internal changes required to support Unicode caused a major overhaul that touched nearly the entire implementation. At the same time, the code base was cleaned up so it could be used in multi-threaded environments, and it added a platform-independent dynamic loading facility (i.e., stub libraries). Finally, an all-new regular expression package was added thanks to Henry Spencer. This package brings Advanced Regular Expressions to Tcl, which are already familar to Perl programmers. However, in spite of all these changes, scripts written for earlier versions of Tcl are very compatible with Tcl 8.1.