345 lines
16 KiB
Plaintext
345 lines
16 KiB
Plaintext
Tcl
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SCCS: @(#) README 1.45 97/06/25 11:02:14
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1. Introduction
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---------------
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This directory and its descendants contain the sources and documentation
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for Tcl, an embeddable scripting language. The information here
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corresponds to release 8.0b2, the second (and probably final) beta
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release for Tcl 8.0. Tcl 8.0 is a major new release that replaces the
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core of the interpreter with an on-the-fly bytecode compiler to improve
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execution speed. It also includes several other new features such as
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namespaces and binary I/O, plus many bug fixes. The compiler introduces
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a few incompatibilities that may affect existing Tcl scripts; the
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incompatibilities are relatively obscure but may require modifications
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to some old scripts before they can run with this version. The compiler
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introduces many new C-level APIs, but the old APIs are still supported.
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See below for more details.
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2. Documentation
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----------------
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The best way to get started with Tcl is to read one of the introductory
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books on Tcl:
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Tcl and the Tk Toolkit, by John Ousterhout,
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Addison-Wesley, 1994, ISBN 0-201-63337-X
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Practical Programming in Tcl and Tk, by Brent Welch,
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Prentice-Hall, 1995, ISBN 0-13-182007-9
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Exploring Expect, by Don Libes,
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O'Reilly and Associates, 1995, ISBN 1-56592-090-2
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The "doc" subdirectory in this release contains a complete set of reference
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manual entries for Tcl. Files with extension ".1" are for programs (for
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example, tclsh.1); files with extension ".3" are for C library procedures;
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and files with extension ".n" describe Tcl commands. The file "doc/Tcl.n"
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gives a quick summary of the Tcl language syntax. To print any of the man
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pages, cd to the "doc" directory and invoke your favorite variant of
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troff using the normal -man macros, for example
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ditroff -man Tcl.n
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to print Tcl.n. If Tcl has been installed correctly and your "man"
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program supports it, you should be able to access the Tcl manual entries
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using the normal "man" mechanisms, such as
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man Tcl
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There is also an official home for Tcl and Tk on the Web:
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http://sunscript.sun.com
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These Web pages include information about the latest releases, products
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related to Tcl and Tk, reports on bug fixes and porting issues, HTML
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versions of the manual pages, and pointers to many other Tcl/Tk Web
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pages at other sites. Check them out!
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3. Compiling and installing Tcl
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-------------------------------
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This release contains everything you should need to compile and run
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Tcl under UNIX, Macintoshes, and PCs (either Windows NT, Windows 95,
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or Win 3.1 with Win32s).
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Before trying to compile Tcl you should do the following things:
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(a) Check for a binary release. Pre-compiled binary releases are
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available now for PCs, Macintoshes, and several flavors of UNIX.
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Binary releases are much easier to install than source releases.
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To find out whether a binary release is available for your
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platform, check the home page for SunScript
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(http://sunscript.sun.com) under "Tech Corner". Also, check in
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the FTP directory from which you retrieved the base
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distribution. Some of the binary releases are available freely,
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while others are for sale.
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(b) Make sure you have the most recent patch release. Look in the
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FTP directory from which you retrieved this distribution to see
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if it has been updated with patches. Patch releases fix bugs
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without changing any features, so you should normally use the
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latest patch release for the version of Tcl that you want.
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Patch releases are available in two forms. A file like
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tcl8.0p1.tar.Z is a complete release for patch level 1 of Tcl
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version 8.0. If there is a file with a higher patch level than
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this release, just fetch the file with the highest patch level
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and use it.
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Patches are also available in the form of patch files that just
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contain the changes from one patch level to another. These
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files will have names like tcl8.0p1.patch, tcl8.0p2.patch, etc. They
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may also have .gz or .Z extensions to indicate compression. To
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use one of these files, you apply it to an existing release with
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the "patch" program. Patches must be applied in order:
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tcl8.0p1.patch must be applied to an unpatched Tcl 8.0 release
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to produce a Tcl 8.0p1 release; tcl8.0p2.patch can then be
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applied to Tcl8.0p1 to produce Tcl 8.0p2, and so on. To apply an
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uncompressed patch file such as tcl8.0p1.patch, invoke a shell
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command like the following from the directory containing this
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file:
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patch -p < tcl8.0p1.patch
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If the patch file has a .gz extension, invoke a command like the
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following:
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gunzip -c tcl8.0p1.patch.gz | patch -p
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If the patch file has a .Z extension, it was compressed with
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compress. To apply it, invoke a command like the following:
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zcat tcl8.0p1.patch.Z | patch -p
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If you're applying a patch to a release that has already been
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compiled, then before applying the patch you should cd to the
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"unix" subdirectory and type "make distclean" to restore the
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directory to a pristine state.
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Once you've done this, change to the "unix" subdirectory if you're
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compiling under UNIX, "win" if you're compiling under Windows, or
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"mac" if you're compiling on a Macintosh. Then follow the instructions
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in the README file in that directory for compiling Tcl, installing it,
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and running the test suite.
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4. Summary of changes in Tcl 8.0
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--------------------------------
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Here are the most significant changes in Tcl 8.0. In addition to these
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changes, there are several smaller changes and bug fixes. See the file
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"changes" for a complete list of all changes.
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1. Bytecode compiler. The core of the Tcl interpreter has been
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replaced with an on-the-fly compiler that translates Tcl scripts to
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byte codes; a new interpreter then executes the byte codes. In
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earlier versions of Tcl, strings were used as a universal
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representation; in Tcl 8.0 strings are replaced with Tcl_Obj
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structures ("objects") that can hold both a string value and an
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internal form such as a binary integer or compiled bytecodes. The
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new objects make it possible to store information in efficient
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internal forms and avoid the constant translations to and from
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strings that occurred with the old interpreter. We have not yet
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converted all of Tcl to take full advantage of the compiler and
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objects and have not converted any of Tk yet, but even so you
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should see speedups of 2-3x on many programs and you may see
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speedups as much as 10-20x in some cases (such as code that
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manipulates long lists). Future releases should achieve even
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greater speedups. The compiler introduces only a few minor changes
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at the level of Tcl scripts, but it introduces many new C APIs for
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managing objects. See, for example, the manual entries doc/*Obj*.3.
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2. Namespaces. There is a new namespace mechanism based on the
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namespace implementation by Michael McLennan of Lucent Technologies.
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This includes new "namespace" and "variable" commands. There are
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many new C APIs associated with namespaces, but they will not be
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exported until Tcl 8.1. Note: the syntax of the namespace command
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has been changed slightly since the b1 release. See the changes
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file for details.
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3. Binary I/O. The new object system in Tcl 8.0 supports binary
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strings (internally, strings are counted in addition to being null
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terminated). There is a new "binary" command for inserting and
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extracting data to/from binary strings. Commands such as "puts",
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"gets", and "read" commands now operate correctly on binary data.
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There is a new variable tcl_platform(byteOrder) to identify the
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native byte order for the current host.
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4. Random numbers. The "expr" command now contains a random number
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generator, which can be accessed via the "rand()" and "srand()" math
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functions.
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5. Safe-Tcl enhancements. There is a new "hidden command"
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mechanism, implemented with the Tcl commands "interp hide", "interp
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expose", "interp invokehidden", and "interp hidden" and the C APIs
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Tcl_HideCommand and Tcl_ExposeCommand. There is now support for
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loadable security policies, including new library procedures such as
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tcl_safeCreateInterp.
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6. There is a new package "registry" available under Windows for
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accessing the Windows registry.
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7. There is a new command "file attributes" for getting and setting
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things like permissions and owner. There is also a new command
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"file nativename" for getting back the platform-specific name for a
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particular file.
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8. There is a new "fcopy" command to copy data between channels.
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This replaces and improves upon the not-so-secret unsupported old
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command "unsupported0".
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9. There is a new package "http" for doing GET, POST, and HEAD
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requests via the HTTP/1.0 protocol. See the manual entry http.n
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for details.
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10. There are new library procedures for finding word breaks in
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strings. See the manual entry library.n for details.
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11. There are new C APIs Tcl_Finalize (for cleaning up before
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unloading the Tcl DLL) and Tcl_Ungets for pushing bytes back into a
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channel's input buffer.
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12. Tcl now supports serial I/O devices on Windows and Unix, with a
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new fconfigure -mode option. The Windows driver does not yet
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support event-driven I/O.
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13. The lsort command has new options -dictionary and -index. The
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-index option allows for very rapid sorting based on an element
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of a list.
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14. The event notifier has been completely rewritten (again). It
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should now allow Tcl to use an external event loop (like Motif's)
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when it is embedded in other applications. No script-level
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interfaces have changed, but many of the C APIs have.
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Tcl 8.0 introduces the following incompatibilities that may affect Tcl
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scripts that worked under Tcl 7.6 and earlier releases:
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1. Variable and command names may not include the character sequence
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"::" anymore: this sequence is now used as a namespace separator.
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2. The semantics of some Tcl commands have been changed slightly to
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maximize performance under the compiler. These incompatibilities
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are documented on the Web so that we can keep the list up-to-date.
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See the URL http://www.sunlabs.com/research/tcl/compiler.html.
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3. 2-digit years are now parsed differently by the "clock" command
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to handle year 2000 issues better (years 00-38 are treated as
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2000-2038 instead of 1900-1938).
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4. The old Macintosh commands "cp", "mkdir", "mv", "rm", and "rmdir"
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are no longer supported; all of these features are now available on
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all platforms via the "file" command.
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5. Support for the variable tcl_precision is mostly removed; when
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real values are converted back to strings, the full 17 digits of
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precision are always used.
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6. The C APIs associated with the notifier have changed substantially.
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7. The procedures Tcl_CreateModalTimeout and Tcl_DeleteModalTimeout
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have been removed.
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8. Tcl_CreateFileHandler and Tcl_DeleteFileHandler now take Unix
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fd's and are only supported on the Unix platform
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9. The C APIs for creating channel drivers have changed as part of
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the new notifier implementation. The Tcl_File interfaces have been
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removed. Tcl_GetChannelFile has been replaced with
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Tcl_GetChannelHandle. Tcl_MakeFileChannel now takes a platform-
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specific file handle. Tcl_DriverGetOptionProc procedures now take
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an additional interp argument.
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5. Tcl newsgroup
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-----------------
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There is a network news group "comp.lang.tcl" intended for the exchange
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of information about Tcl, Tk, and related applications. Feel free to use
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the newsgroup both for general information questions and for bug reports.
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We read the newsgroup and will attempt to fix bugs and problems reported
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to it.
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When using comp.lang.tcl, please be sure that your e-mail return address
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is correctly set in your postings. This allows people to respond directly
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to you, rather than the entire newsgroup, for answers that are not of
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general interest. A bad e-mail return address may prevent you from
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getting answers to your questions. You may have to reconfigure your news
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reading software to ensure that it is supplying valid e-mail addresses.
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6. Tcl contributed archive
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--------------------------
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Many people have created exciting packages and applications based on Tcl
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and/or Tk and made them freely available to the Tcl community. An archive
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of these contributions is kept on the machine ftp.neosoft.com. You
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can access the archive using anonymous FTP; the Tcl contributed archive is
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in the directory "/pub/tcl". The archive also contains several FAQ
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("frequently asked questions") documents that provide solutions to problems
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that are commonly encountered by TCL newcomers.
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7. Support and bug fixes
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------------------------
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We're very interested in receiving bug reports and suggestions for
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improvements. We prefer that you send this information to the
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comp.lang.tcl newsgroup rather than to any of us at Sun. We'll see
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anything on comp.lang.tcl, and in addition someone else who reads
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comp.lang.tcl may be able to offer a solution. The normal turn-around
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time for bugs is 3-6 weeks. Enhancements may take longer and may not
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happen at all unless there is widespread support for them (we're
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trying to slow the rate at which Tcl turns into a kitchen sink). It's
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very difficult to make incompatible changes to Tcl at this point, due
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to the size of the installed base.
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When reporting bugs, please provide a short tclsh script that we can
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use to reproduce the bug. Make sure that the script runs with a
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bare-bones tclsh and doesn't depend on any extensions or other
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programs, particularly those that exist only at your site. Also,
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please include three additional pieces of information with the
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script:
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(a) how do we use the script to make the problem happen (e.g.
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what things do we click on, in what order)?
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(b) what happens when you do these things (presumably this is
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undesirable)?
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(c) what did you expect to happen instead?
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The Tcl community is too large for us to provide much individual
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support for users. If you need help we suggest that you post questions
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to comp.lang.tcl. We read the newsgroup and will attempt to answer
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esoteric questions for which no-one else is likely to know the answer.
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In addition, Tcl support and training are available commercially from
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NeoSoft (info@neosoft.com), Computerized Processes Unlimited
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(gwl@cpu.com), and Data Kinetics (education@dkl.com).
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8. Tcl version numbers
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----------------------
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Each Tcl release is identified by two numbers separated by a dot, e.g.
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6.7 or 7.0. If a new release contains changes that are likely to break
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existing C code or Tcl scripts then the major release number increments
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and the minor number resets to zero: 6.0, 7.0, etc. If a new release
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contains only bug fixes and compatible changes, then the minor number
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increments without changing the major number, e.g. 7.1, 7.2, etc. If
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you have C code or Tcl scripts that work with release X.Y, then they
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should also work with any release X.Z as long as Z > Y.
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Alpha and beta releases have an additional suffix of the form a2 or b1.
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For example, Tcl 7.0b1 is the first beta release of Tcl version 7.0,
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Tcl 7.0b2 is the second beta release, and so on. A beta release is an
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initial version of a new release, used to fix bugs and bad features before
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declaring the release stable. An alpha release is like a beta release,
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except it's likely to need even more work before it's "ready for prime
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time". New releases are normally preceded by one or more alpha and beta
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releases. We hope that lots of people will try out the alpha and beta
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releases and report problems. We'll make new alpha/beta releases to fix
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the problems, until eventually there is a beta release that appears to
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be stable. Once this occurs we'll make the final release.
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We can't promise to maintain compatibility among alpha and beta releases.
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For example, release 7.1b2 may not be backward compatible with 7.1b1, even
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though the final 7.1 release will be backward compatible with 7.0. This
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allows us to change new features as we find problems during beta testing.
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We'll try to minimize incompatibilities between beta releases, but if
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a major problem turns up then we'll fix it even if it introduces an
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incompatibility. Once the official release is made then there won't
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be any more incompatibilities until the next release with a new major
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version number.
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Patch releases have a suffix such as p1 or p2. These releases contain
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bug fixes only. A patch release (e.g Tcl 7.6p2) should be completely
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compatible with the base release from which it is derived (e.g. Tcl
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7.6), and you should normally use the highest available patch release.
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