332 lines
16 KiB
Plaintext
332 lines
16 KiB
Plaintext
Tcl
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by John Ousterhout (and many others at Sun Microsystems and elsewhere)
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john.ousterhout@eng.sun.com
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SCCS: @(#) README 1.29 96/04/19 11:42:58
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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 corresponds
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to release 7.5. The most important new feature in this release is support
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for the PC and Mac platforms. In addition, there are major new facilities
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for dynamic loading, package and version management, multiple interpreters,
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safe execution of untrusted scripts, and a new I/O system that supports
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nonblocking I/O and sockets. This release also contains many bug fixes.
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Tcl 7.5 should be backwards compatible with Tcl 7.4 scripts (there are two
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small incompatibilities described below, but they are relatively insignificant
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and shouldn't affect most existing Tcl code and extensions).
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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://www.sunlabs.com/research/tcl
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These Web pages include release updates, reports on bug fixes and porting
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issues, HTML versions of the manual pages, and pointers to many other
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Tcl/Tk Web 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 and Macintoshes, and they may be available
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in the future for some flavors of UNIX. Binary releases are much
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easier to install than source releases. To find out whether a
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binary release is available for your platform, check the home page
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for the Sun Tcl/Tk project (http://www.sunlabs.com/research/tcl)
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and also check in the FTP directory from which you retrieved the
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base distribution.
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(b) Check for patches. Look in the FTP directory from which you
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retrieved the base distribution and see if there are files with
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names like tcl7.5p1.patch, tcl7.5p2.patch, etc. These files may
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also have .gz or .Z extensions to indicate compression. If you find
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any patch files, apply them to the source directory in order
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from "p1" up. To apply an uncompressed patch file such as
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tcl7.5p1.patch, invoke a shell command like the following from
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the directory containing this file:
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patch -p < tcl7.5p1.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 tcl7.5p1.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 tcl7.5p1.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 7.5
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--------------------------------
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The most important change for Tcl 7.5 is that Tcl now runs on Macintosh
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and PC platforms as well as UNIX. The PC port runs under Windows 3.1
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(with Win32s), Windows 95, and Windows NT. This required a lot of
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reorganization of the sources but it didn't require any changes to
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Tcl's externally visible interfaces.
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In addition to the ports, Tcl 7.5 also has many other new features.
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The following feature changes have occurred since Tcl 7.4:
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1. Dynamic loading. There is a new "load" command for loading binary
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extensions into Tcl on the fly. This works now on most of the major
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UNIX platforms as well as PCs and Macintoshes. Three new "info"
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commands, "info loaded", "info sharedlibextension", and
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"info nameofexecutable", were also added as part of the dynamic loading
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implementation. You can also create Tcl and Tk themselves as shared
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libraries with the --enable-shared switch to the configure script.
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2. Packages and versions. There is a new "package" command for
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package and version management. See the manual entries for "package"
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and "pkg_mkIndex" for details on how to use it. There are also
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C APIs to the package mechanism. See PkgRequire.3.
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3. Multiple interpreters and Safe-Tcl. There is a new "interp" command
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that allows you to create multiple interpreters within a single application
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and set up communication between them with "aliases". The mechanism also
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supports "safe" interpreters, which provide a generalized version of the
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security mechanisms in Borenstein and Rose's Safe-Tcl. There are still
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a few missing security features, such as resource control. You can use
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"load" to add extensions (including Tk) into slave interpreters.
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4. The event loop from Tk has been moved to Tcl. Tcl now has commands
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"after", "fileevent", "update", and "vwait" (which replaces tkwait).
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The "tkerror" command has been renamed to "bgerror". "Tkerror" is
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still supported for backwards compatibility, but you should switch ASAP
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to using "bgerror" instead. Many C procedures that used to be in Tk
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have been moved to Tcl and renamed, such as Tcl_DoOneEvent, Tcl_DoWhenIdle,
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Tcl_CreateFileHandler, and Tcl_CreateTimerHandler.
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5. Tcl has a whole new I/O system. All of the Tcl commands like
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"open" and "puts" should continue to operate as before, but there
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is a totally new implementation that doesn't use the C stdio library:
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- The new I/O system is more portable, and it can be extended
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with new kinds of I/O channels; see CrtChannel.3 for details.
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- Nonblocking I/O is supported on all platforms and there is a
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new command "fconfigure" to enable it and other channel options;
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see fconfigure.n for details. There is also a new "fblocked"
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command.
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- The I/O system automatically translates between different
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end-of-line representations (such as CR on Macs and CRLF on
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PC's) to the newline form used in UNIX and in all Tcl scripts;
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the "fconfigure" command can be used to control this feature.
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- There is a set of C APIs for manipulating Tcl_Channel's, which
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are analogous to UNIX FILE's. The C procedures have roughly the
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same functionality as the stdio procedures. See OpenFileChnl.3,
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CrtCloseHdlr.3, and CrtChnlHdlr.3 for details.
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- There is a new structure Tcl_File that provides platform-
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independent access to file handles such as UNIX fd's. See
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GetFile.3 for details.
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- There are new procedures Tcl_GetErrno and Tcl_SetErrno for
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accessing the "errno" variable in a safe and portable fashion.
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See SetErrno.3.
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6. There are new commands "file split", "file join", and "file pathtype",
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which make it possible to handle file names in a way that will work on
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all platforms. See the manual entries file.n and filename.n for
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details.
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7. There is a new "socket" command for network communication via
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TCP sockets. It works for both the client and server sides. There
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is also C-level support for sockets; see OpenTcp.3.
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8. There is a new "clock" command, which contains the functionality
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of the TclX clock-handling commands.
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9. The "foreach" command has been generalized significantly to support
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multiple lists and multiple variables iterating over each list.
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10. There is a new "notifier" mechanism, which was added as part of
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the ports. This allows the basic mechanisms for reporting events
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to be implemented in different ways on different platforms. It
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may also be useful for other purposes, such as merging the Tk and
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Xt event loops so that Tk and Xt widgets can coexist in a single
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application. See the manual entry Notifier.3 for more information.
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11. There is an "AssocData" mechanism that allows extensions to store
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their own data in an interpreter and get called back when the interpreter
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is deleted. This is visible at C level via the procedures Tcl_SetAssocData
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and Tcl_GetAssocData.
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12. When manual pages are installed, additional links are created for
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each of the procedures described in the manual page, so that it's
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easier to invoke the "man" command.
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13. There is a new variable "tcl_platform" with platform information.
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This is an associative array with elements like "os" and "machine"
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that contain various pieces of information about the platform.
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14. There is a new procedure Tcl_CreateExitHandler that you can use to
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make sure a C procedure is called before the Tcl application exits.
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15. There is a new procedure Tcl_UpdateLinkedVar to force the Tcl-level
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variable to be updated after you've changed the corresponding C-level
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variable.
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16. The procedures Tk_Preserve, Tk_Release, and Tk_EventuallyFree
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have been moved from Tk to Tcl and given names like Tcl_Preserve.
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Three incompatibilities were introduced by the changes. All of these
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are at C-level, and only the first one should have much impact. Existing
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scripts for Tcl 7.4 should run unchanged under Tcl 7.5.
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1. The procedure Tcl_EnterFile no longer exists. However, a new
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procedure Tcl_MakeFileChannel provides similar functionality.
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Tcl_GetOpenFile still exists but only works under UNIX.
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Tcl_CreatePipeline also remains, but it too works only under UNIX
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now; use Tcl_OpenCommandChannel for better portability.
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2. Tcl doesn't export any global C variables anymore, because this doesn't
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work with Windows DLLs. The C variables tcl_AsyncReady and
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tcl_FileCloseProc have been replaced with procedures Tcl_AsyncReady()
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and Tcl_SetFileCloseProc(). The C variable tcl_RcFileName has been
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replaced with a Tcl variable tcl_rcFileName (use Tcl_SetVar to set the
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Tcl variable, instead of assigning to the old C variable).
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3. Files are no longer shared between interpreters by default: if a
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file is opened in one interpreter, it cannot normally be used in other
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interpreters. However, the new procedure Tcl_ShareHandle allows files
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to be shared between interpreters if requested explicitly.
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For a complete list of all changes in this release, see the file "changes"
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in this directory.
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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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omp.lang.tcl may be able to offer a solution. The normal turn-around
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time for bugs is 2-4 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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