Tcl Source Code

The source code for Tcl is managed by fossil. Tcl developers coordinate all changes to the Tcl source code at

Tcl Source Code

Release Tcl 8.7b1 arises from the check-in with tag core-8.7-b1.

Highlighted differences between Tcl 8.7 and Tcl 8.6 are summarized below, with focus on changes important to programmers using the Tcl library and writing Tcl scripts.

Internationalization of text

• Full Unicode range of codepoints
• New encodings: utf-16/utf-32/ucs-2(le|be), CESU-8, etc.
• encoding options -profile, -failindex manage encoding of I/O.
• msgcat supports custom locale search list
• source defaults to -encoding utf-8

Zip filesystems and attached archives.

Unix notifiers available using epoll() or kqueue()

• relieves limits on file descriptors imposed by legacy select()

Notable incompatibilities

• No --disable-threads build option. Always thread-enabled.
• Windows platform needs Windows 7 or Windows Server 2008 R2 or later

New commands

• array default, array for
• chan isbinary
• coroinject, coroprobe
• clock add weekdays
• dict getwithdefault
• file tempdir, file home, file tildeexpand
• info commandtype
• ledit
• lpop
• lremove
• lseq
• package files
• string insert, string is dict
• tcl::process
• *::build-info
• readFile, writeFile, foreachLine

New command options

• clock scan ... -validate ...
• info loaded ... ?prefix?
• lsearch ... -stride ...
• regsub ... -command ...
• socket ... -nodelay ... -keepalive ...
• vwait controlled by several new options

Numbers

• 0dNNNN format to compel decimal interpretation.
• NN_NNN_NNN, underscores in numbers for optional readability
• Functions: isinf() isnan() isnormal() issubnormal() isunordered()
• fpclassify
• Function int() no longer truncates to word size

tcl::oo facilities

• private variable and methods
• method -export, method -unexport