Tcl SCCS: @(#) README 1.52 97/11/20 12:43:16 1. Introduction --------------- This directory and its descendants contain the sources and documentation for Tcl, an embeddable scripting language. The information here corresponds to release 8.0p2, which is the second patch update for Tcl 8.0. Tcl 8.0 is a major new release that replaces the core of the interpreter with an on-the-fly bytecode compiler to improve execution speed. It also includes several other new features such as namespaces and binary I/O, plus many bug fixes. The compiler introduces a few incompatibilities that may affect existing Tcl scripts; the incompatibilities are relatively obscure but may require modifications to some old scripts before they can run with this version. The compiler introduces many new C-level APIs, but the old APIs are still supported. See below for more details. This patch release fixes various bugs in Tcl 8.0; there are no feature changes relative to Tcl 8.0. 2. Documentation ---------------- The best way to get started with Tcl is to read one of the introductory books on Tcl: Practical Programming in Tcl and Tk, 2nd Edition, by Brent Welch, Prentice-Hall, 1997, ISBN 0-13-616830-2 Tcl and the Tk Toolkit, by John Ousterhout, Addison-Wesley, 1994, ISBN 0-201-63337-X Exploring Expect, by Don Libes, O'Reilly and Associates, 1995, ISBN 1-56592-090-2 The "doc" subdirectory in this release contains a complete set of reference manual entries for Tcl. Files with extension ".1" are for programs (for example, tclsh.1); files with extension ".3" are for C library procedures; and files with extension ".n" describe Tcl commands. The file "doc/Tcl.n" gives a quick summary of the Tcl language syntax. To print any of the man pages, cd to the "doc" directory and invoke your favorite variant of troff using the normal -man macros, for example ditroff -man Tcl.n to print Tcl.n. If Tcl has been installed correctly and your "man" program supports it, you should be able to access the Tcl manual entries using the normal "man" mechanisms, such as man Tcl There is also an official home for Tcl and Tk on the Web: http://sunscript.sun.com These Web pages include information about the latest releases, products related to Tcl and Tk, reports on bug fixes and porting issues, HTML versions of the manual pages, and pointers to many other Tcl/Tk Web pages at other sites. Check them out! 3. Compiling and installing Tcl ------------------------------- This release contains everything you should need to compile and run Tcl under UNIX, Macintoshes, and PCs (either Windows NT, Windows 95, or Win 3.1 with Win32s). Before trying to compile Tcl you should do the following things: (a) Check for a binary release. Pre-compiled binary releases are available now for PCs, Macintoshes, and several flavors of UNIX. Binary releases are much easier to install than source releases. To find out whether a binary release is available for your platform, check the home page for SunScript (http://sunscript.sun.com) under "Tech Corner". Also, check in the FTP directory from which you retrieved the base distribution. Some of the binary releases are available freely, while others are for sale. (b) Make sure you have the most recent patch release. Look in the FTP directory from which you retrieved this distribution to see if it has been updated with patches. Patch releases fix bugs without changing any features, so you should normally use the latest patch release for the version of Tcl that you want. Patch releases are available in two forms. A file like tcl8.0p2.tar.Z is a complete release for patch level 2 of Tcl version 8.0. If there is a file with a higher patch level than this release, just fetch the file with the highest patch level and use it. Patches are also available in the form of patch files that just contain the changes from one patch level to another. These files will have names like tcl8.0p1.patch, tcl8.0p2.patch, etc. They may also have .gz or .Z extensions to indicate compression. To use one of these files, you apply it to an existing release with the "patch" program. Patches must be applied in order: tcl8.0p1.patch must be applied to an unpatched Tcl 8.0 release to produce a Tcl 8.0p1 release; tcl8.0p2.patch can then be applied to Tcl8.0p1 to produce Tcl 8.0p2, and so on. To apply an uncompressed patch file such as tcl8.0p1.patch, invoke a shell command like the following from the directory containing this file: patch -p0 < tcl8.0p1.patch If the patch file has a .gz extension, invoke a command like the following: gunzip -c tcl8.0p1.patch.gz | patch -p0 If the patch file has a .Z extension, it was compressed with compress. To apply it, invoke a command like the following: zcat tcl8.0p1.patch.Z | patch -p0 If you're applying a patch to a release that has already been compiled, then before applying the patch you should cd to the "unix" subdirectory and type "make distclean" to restore the directory to a pristine state. Once you've done this, change to the "unix" subdirectory if you're compiling under UNIX, "win" if you're compiling under Windows, or "mac" if you're compiling on a Macintosh. Then follow the instructions in the README file in that directory for compiling Tcl, installing it, and running the test suite. 4. Summary of changes in Tcl 8.0 -------------------------------- Here are the most significant changes in Tcl 8.0. In addition to these changes, there are several smaller changes and bug fixes. See the file "changes" for a complete list of all changes. 1. Bytecode compiler. The core of the Tcl interpreter has been replaced with an on-the-fly compiler that translates Tcl scripts to byte codes; a new interpreter then executes the byte codes. In earlier versions of Tcl, strings were used as a universal representation; in Tcl 8.0 strings are replaced with Tcl_Obj structures ("objects") that can hold both a string value and an internal form such as a binary integer or compiled bytecodes. The new objects make it possible to store information in efficient internal forms and avoid the constant translations to and from strings that occurred with the old interpreter. We have not yet converted all of Tcl to take full advantage of the compiler and objects and have not converted any of Tk yet, but even so you should see speedups of 2-3x on many programs and you may see speedups as much as 10-20x in some cases (such as code that manipulates long lists). Future releases should achieve even greater speedups. The compiler introduces only a few minor changes at the level of Tcl scripts, but it introduces many new C APIs for managing objects. See, for example, the manual entries doc/*Obj*.3. 2. Namespaces. There is a new namespace mechanism based on the namespace implementation by Michael McLennan of Lucent Technologies. This includes new "namespace" and "variable" commands. There are many new C APIs associated with namespaces, but they will not be exported until Tcl 8.1. Note: the syntax of the namespace command has been changed slightly since the b1 release. See the changes file for details. 3. Binary I/O. The new object system in Tcl 8.0 supports binary strings (internally, strings are counted in addition to being null terminated). There is a new "binary" command for inserting and extracting data to/from binary strings. Commands such as "puts", "gets", and "read" commands now operate correctly on binary data. There is a new variable tcl_platform(byteOrder) to identify the native byte order for the current host. 4. Random numbers. The "expr" command now contains a random number generator, which can be accessed via the "rand()" and "srand()" math functions. 5. Safe-Tcl enhancements. There is a new "hidden command" mechanism, implemented with the Tcl commands "interp hide", "interp expose", "interp invokehidden", and "interp hidden" and the C APIs Tcl_HideCommand and Tcl_ExposeCommand. There is now support for safe packages and extension loading, including new library procedures such as safe::interpCreate (see the manual entry safe.n for details). 6. There is a new package "registry" available under Windows for accessing the Windows registry. 7. There is a new command "file attributes" for getting and setting things like permissions and owner. There is also a new command "file nativename" for getting back the platform-specific name for a particular file. 8. There is a new "fcopy" command to copy data between channels. This replaces and improves upon the not-so-secret unsupported old command "unsupported0". 9. There is a new package "http" for doing GET, POST, and HEAD requests via the HTTP/1.0 protocol. See the manual entry http.n for details. 10. There are new library procedures for finding word breaks in strings. See the manual entry library.n for details. 11. There are new C APIs Tcl_Finalize (for cleaning up before unloading the Tcl DLL) and Tcl_Ungets for pushing bytes back into a channel's input buffer. 12. Tcl now supports serial I/O devices on Windows and Unix, with a new fconfigure -mode option. The Windows driver does not yet support event-driven I/O. 13. The lsort command has new options -dictionary and -index. The -index option allows for very rapid sorting based on an element of a list. 14. The event notifier has been completely rewritten (again). It should now allow Tcl to use an external event loop (like Motif's) when it is embedded in other applications. No script-level interfaces have changed, but many of the C APIs have. Tcl 8.0 introduces the following incompatibilities that may affect Tcl scripts that worked under Tcl 7.6 and earlier releases: 1. Variable and command names may not include the character sequence "::" anymore: this sequence is now used as a namespace separator. 2. The semantics of some Tcl commands have been changed slightly to maximize performance under the compiler. These incompatibilities are documented on the Web so that we can keep the list up-to-date. See the URL http://www.sunlabs.com/research/tcl/compiler.html. 3. 2-digit years are now parsed differently by the "clock" command to handle year 2000 issues better (years 00-38 are treated as 2000-2038 instead of 1900-1938). 4. The old Macintosh commands "cp", "mkdir", "mv", "rm", and "rmdir" are no longer supported; all of these features are now available on all platforms via the "file" command. 5. The variable tcl_precision is now shared between interpreters and defaults to 12 digits instead of 6; safe interpreters cannot modify tcl_precision. The new object system in Tcl 8.0 causes floating-to-string conversions (and the associated rounding) to occur much less often than in Tcl 7.6, which can sometimes cause behavioral changes. 6. The C APIs associated with the notifier have changed substantially. 7. The procedures Tcl_CreateModalTimeout and Tcl_DeleteModalTimeout have been removed. 8. Tcl_CreateFileHandler and Tcl_DeleteFileHandler now take Unix fd's and are only supported on the Unix platform 9. The C APIs for creating channel drivers have changed as part of the new notifier implementation. The Tcl_File interfaces have been removed. Tcl_GetChannelFile has been replaced with Tcl_GetChannelHandle. Tcl_MakeFileChannel now takes a platform- specific file handle. Tcl_DriverGetOptionProc procedures now take an additional interp argument. 5. Tcl newsgroup ----------------- There is a network news group "comp.lang.tcl" intended for the exchange of information about Tcl, Tk, and related applications. Feel free to use the newsgroup both for general information questions and for bug reports. We read the newsgroup and will attempt to fix bugs and problems reported to it. When using comp.lang.tcl, please be sure that your e-mail return address is correctly set in your postings. This allows people to respond directly to you, rather than the entire newsgroup, for answers that are not of general interest. A bad e-mail return address may prevent you from getting answers to your questions. You may have to reconfigure your news reading software to ensure that it is supplying valid e-mail addresses. 6. Tcl contributed archive -------------------------- Many people have created exciting packages and applications based on Tcl and/or Tk and made them freely available to the Tcl community. An archive of these contributions is kept on the machine ftp.neosoft.com. You can access the archive using anonymous FTP; the Tcl contributed archive is in the directory "/pub/tcl". The archive also contains several FAQ ("frequently asked questions") documents that provide solutions to problems that are commonly encountered by TCL newcomers. 7. Mailing lists ---------------- A couple of Mailing List have been set up to discuss Macintosh or Windows related Tcl issues. In order to use these Mailing Lists you must have access to the internet. If you have access to the WWW the home pages for these mailing lists are located at the following URLs: http://www.sunlabs.com/research/tcl/lists/mactcl-list.html -and- http://www.sunlabs.com/research/tcl/lists/wintcl-list.html The home pages contain information about the lists and an HTML archive of all the past messages on the list. To subscribe send a message to: listserv@sunlabs.sun.com In the body of the message (the subject will be ignored) put: subscribe mactcl Joe Blow Replacing Joe Blow with your real name, of course. (Use wintcl instead of mactcl if your interested in the Windows list.) If you would just like to receive more information about the list without subscribing put the line: information mactcl in the body instead (or wintcl). 8. Support and bug fixes ------------------------ We're very interested in receiving bug reports and suggestions for improvements. We prefer that you send this information to the comp.lang.tcl newsgroup rather than to any of us at Sun. We'll see anything on comp.lang.tcl, and in addition someone else who reads comp.lang.tcl may be able to offer a solution. The normal turn-around time for bugs is 3-6 weeks. Enhancements may take longer and may not happen at all unless there is widespread support for them (we're trying to slow the rate at which Tcl turns into a kitchen sink). It's very difficult to make incompatible changes to Tcl at this point, due to the size of the installed base. When reporting bugs, please provide a short tclsh script that we can use to reproduce the bug. Make sure that the script runs with a bare-bones tclsh and doesn't depend on any extensions or other programs, particularly those that exist only at your site. Also, please include three additional pieces of information with the script: (a) how do we use the script to make the problem happen (e.g. what things do we click on, in what order)? (b) what happens when you do these things (presumably this is undesirable)? (c) what did you expect to happen instead? The Tcl community is too large for us to provide much individual support for users. If you need help we suggest that you post questions to comp.lang.tcl. We read the newsgroup and will attempt to answer esoteric questions for which no-one else is likely to know the answer. In addition, Tcl support and training are available commercially from NeoSoft (info@neosoft.com), Computerized Processes Unlimited (gwl@cpu.com), and Data Kinetics (education@dkl.com). 9. Tcl version numbers ---------------------- Each Tcl release is identified by two numbers separated by a dot, e.g. 6.7 or 7.0. If a new release contains changes that are likely to break existing C code or Tcl scripts then the major release number increments and the minor number resets to zero: 6.0, 7.0, etc. If a new release contains only bug fixes and compatible changes, then the minor number increments without changing the major number, e.g. 7.1, 7.2, etc. If you have C code or Tcl scripts that work with release X.Y, then they should also work with any release X.Z as long as Z > Y. Alpha and beta releases have an additional suffix of the form a2 or b1. For example, Tcl 7.0b1 is the first beta release of Tcl version 7.0, Tcl 7.0b2 is the second beta release, and so on. A beta release is an initial version of a new release, used to fix bugs and bad features before declaring the release stable. An alpha release is like a beta release, except it's likely to need even more work before it's "ready for prime time". New releases are normally preceded by one or more alpha and beta releases. We hope that lots of people will try out the alpha and beta releases and report problems. We'll make new alpha/beta releases to fix the problems, until eventually there is a beta release that appears to be stable. Once this occurs we'll make the final release. We can't promise to maintain compatibility among alpha and beta releases. For example, release 7.1b2 may not be backward compatible with 7.1b1, even though the final 7.1 release will be backward compatible with 7.0. This allows us to change new features as we find problems during beta testing. We'll try to minimize incompatibilities between beta releases, but if a major problem turns up then we'll fix it even if it introduces an incompatibility. Once the official release is made then there won't be any more incompatibilities until the next release with a new major version number. Patch releases have a suffix such as p1 or p2. These releases contain bug fixes only. A patch release (e.g Tcl 7.6p2) should be completely compatible with the base release from which it is derived (e.g. Tcl 7.6), and you should normally use the highest available patch release.