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diff --git a/doc/package.n b/doc/package.n new file mode 100644 index 0000000..b485caa --- /dev/null +++ b/doc/package.n @@ -0,0 +1,188 @@ +'\" +'\" Copyright (c) 1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" SCCS: @(#) package.n 1.5 96/03/18 14:17:31 +'\" +.so man.macros +.TH package n 7.5 Tcl "Tcl Built-In Commands" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +package \- Facilities for package loading and version control +.SH SYNOPSIS +.nf +\fBpackage forget \fIpackage\fR +\fBpackage ifneeded \fIpackage version\fR ?\fIscript\fR? +\fBpackage names\fR +\fBpackage provide \fIpackage \fR?\fIversion\fR? +\fBpackage require \fR?\fB\-exact\fR? \fIpackage \fR?\fIversion\fR? +\fBpackage unknown \fR?\fIcommand\fR? +\fBpackage vcompare \fIversion1 version2\fR +\fBpackage versions \fIpackage\fR +\fBpackage vsatisfies \fIversion1 version2\fR +.fi +.BE + +.SH DESCRIPTION +.PP +This command keeps a simple database of the packages available for +use by the current interpreter and how to load them into the +interpreter. +It supports multiple versions of each package and arranges +for the correct version of a package to be loaded based on what +is needed by the application. +This command also detects and reports version clashes. +Typically, only the \fBpackage require\fR and \fBpackage provide\fR +commands are invoked in normal Tcl scripts; the other commands are used +primarily by system scripts that maintain the package database. +.PP +The behavior of the \fBpackage\fR command is determined by its first argument. +The following forms are permitted: +.TP +\fBpackage forget \fIpackage\fR +Removes all information about \fIpackage\fR from this interpreter, +including information provided by both \fBpackage ifneeded\fR and +\fBpackage provide\fR. +.TP +\fBpackage ifneeded \fIpackage version\fR ?\fIscript\fR? +This command typically appears only in system configuration +scripts to set up the package database. +It indicates that a particular version of +a particular package is available if needed, and that the package +can be added to the interpreter by executing \fIscript\fR. +The script is saved in a database for use by subsequent +\fBpackage require\fR commands; typically, \fIscript\fR +sets up auto-loading for the commands in the package (or calls +\fBload\fR and/or \fBsource\fR directly), then invokes +\fBpackage provide\fR to indicate that the package is present. +There may be information in the database for several different +versions of a single package. +If the database already contains information for \fIpackage\fR +and \fIversion\fR, the new \fIscript\fR replaces the existing +one. +If the \fIscript\fR argument is omitted, the current script for +version \fIversion\fR of package \fIpackage\fR is returned, +or an empty string if no \fBpackage ifneeded\fR command has +been invoked for this \fIpackage\fR and \fIversion\fR. +.TP +\fBpackage names\fR +Returns a list of the names of all packages in the +interpreter for which a version has been provided (via +\fBpackage provide\fR) or for which a \fBpackage ifneeded\fR +script is available. +The order of elements in the list is arbitrary. +.TP +\fBpackage provide \fIpackage \fR?\fIversion\fR? +This command is invoked to indicate that version \fIversion\fR +of package \fIpackage\fR is now present in the interpreter. +It is typically invoked once as part of an \fBifneeded\fR script, +and again by the package itself when it is finally loaded. +An error occurs if a different version of \fIpackage\fR has been +provided by a previous \fBpackage provide\fR command. +If the \fIversion\fR argument is omitted, then the command +returns the version number that is currently provided, or an +empty string if no \fBpackage provide\fR command has been +invoked for \fIpackage\fR in this interpreter. +.TP +\fBpackage require \fR?\fB\-exact\fR? \fIpackage \fR?\fIversion\fR? +This command is typically invoked by Tcl code that wishes to use +a particular version of a particular package. The arguments +indicate which package is wanted, and the command ensures that +a suitable version of the package is loaded into the interpreter. +If the command succeeds, it returns the version number that is +loaded; otherwise it generates an error. +If both the \fB\-exact\fR +switch and the \fIversion\fR argument are specified then only the +given version is acceptable. If \fB\-exact\fR is omitted but +\fIversion\fR is specified, then versions later than \fIversion\fR +are also acceptable as long as they have the same major version +number as \fIversion\fR. +If both \fB\-exact\fR and \fIversion\fR are omitted then any +version whatsoever is acceptable. +If a version of \fIpackage\fR has already been provided (by invoking +the \fBpackage provide\fR command), then its version number must +satisfy the criteria given by \fB\-exact\fR and \fIversion\fR and +the command returns immediately. +Otherwise, the command searches the database of information provided by +previous \fBpackage ifneeded\fR commands to see if an acceptable +version of the package is available. +If so, the script for the highest acceptable version number is invoked; +it must do whatever is necessary to load the package, +including calling \fBpackage provide\fR for the package. +If the \fBpackage ifneeded\fR database does not contain an acceptable +version of the package and a \fBpackage unknown\fR command has been +specified for the interpreter then that command is invoked; when +it completes, Tcl checks again to see if the package is now provided +or if there is a \fBpackage ifneeded\fR script for it. +If all of these steps fail to provide an acceptable version of the +package, then the command returns an error. +.TP +\fBpackage unknown \fR?\fIcommand\fR? +This command supplies a ``last resort'' command to invoke during +\fBpackage require\fR if no suitable version of a package can be found +in the \fBpackage ifneeded\fR database. +If the \fIcommand\fR argument is supplied, it contains the first part +of a command; when the command is invoked during a \fBpackage require\fR +command, Tcl appends two additional arguments giving the desired package +name and version. +For example, if \fIcommand\fR is \fBfoo bar\fR and later the command +\fBpackage require test 2.4\fR is invoked, then Tcl will execute +the command \fBfoo bar test 2.4\fR to load the package. +If no version number is supplied to the \fBpackage require\fR command, +then the version argument for the invoked command will be an empty string. +If the \fBpackage unknown\fR command is invoked without a \fIcommand\fR +argument, then the current \fBpackage unknown\fR script is returned, +or an empty string if there is none. +If \fIcommand\fR is specified as an empty string, then the current +\fBpackage unknown\fR script is removed, if there is one. +.TP +\fBpackage vcompare \fIversion1 version2\fR +Compares the two version numbers given by \fIversion1\fR and \fIversion2\fR. +Returns -1 if \fIversion1\fR is an earlier version than \fIversion2\fR, +0 if they are equal, and 1 if \fIversion1\fR is later than \fBversion2\fR. +.TP +\fBpackage versions \fIpackage\fR +Returns a list of all the version numbers of \fIpackage\fR +for which information has been provided by \fBpackage ifneeded\fR +commands. +.TP +\fBpackage vsatisfies \fIversion1 version2\fR +Returns 1 if scripts written for \fIversion2\fR will work unchanged +with \fIversion1\fR (i.e. \fIversion1\fR is equal to or greater +than \fIversion2\fR and they both have the same major version +number), 0 otherwise. + +.SH "VERSION NUMBERS" +.PP +Version numbers consist of one or more decimal numbers separated +by dots, such as 2 or 1.162 or 3.1.13.1. +The first number is called the major version number. +Larger numbers correspond to later versions of a package, with +leftmost numbers having greater significance. +For example, version 2.1 is later than 1.3 and version +3.4.6 is later than 3.3.5. +Missing fields are equivalent to zeroes: version 1.3 is the +same as version 1.3.0 and 1.3.0.0, so it is earlier than 1.3.1 or 1.3.0.2. +A later version number is assumed to be upwards compatible with +an earlier version number as long as both versions have the same +major version number. +For example, Tcl scripts written for version 2.3 of a package should +work unchanged under versions 2.3.2, 2.4, and 2.5.1. +Changes in the major version number signify incompatible changes: +if code is written to use version 2.1 of a package, it is not guaranteed +to work unmodified with either version 1.7.3 or version 3.1. + +.SH "PACKAGE INDICES" +.PP +The recommended way to use packages in Tcl is to invoke \fBpackage require\fR +and \fBpackage provide\fR commands in scripts, and use the procedure +\fBpkg_mkIndex\fR to create package index files. +Once you've done this, packages will be loaded automatically +in response to \fBpackage require\fR commands. +See the documentation for \fBpkg_mkIndex\fR for details. + +.SH KEYWORDS +package, version |