Other Tcl Changes

Unsetting Nonexistent Variables

With the -nocomplain option, unset suppresses any possible errors. A new -- option also allows you to delete variables that might have the same name as any unset options.

Direct Return of Substituted String with regsub

The final regsub argument (the name of the variable in which to store the substituted string) is now optional. If omitted, regsub simply returns the substituted string (or the original string, of no substitutions were made). (TIP #76)

Increased Time Resolution on Windows

Previously, the time command, the clock clicks command, and all related functions were limited to a resolution of (typically) 10 milliseconds on Windows systems. Tcl 8.4 on Windows now features microsecond precision with accuracy in the tens of microseconds. (TIP #7)

Bug Fixed in fcopy to Respect Channel Encodings

The fcopy command in prior versions of Tcl improperly ignored the encodings of the channels. Now fcopy respects the channel encodings, and performs proper translations on the data if the channels have different encodings.