209 lines
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HTML
209 lines
12 KiB
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<HTML><HEAD><TITLE>Tcl Built-In Commands - package manual page</TITLE></HEAD><BODY>
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<DL>
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<DD><A HREF="package.htm#M2" NAME="L789">NAME</A>
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<DL><DD>package - Facilities for package loading and version control</DL>
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<DD><A HREF="package.htm#M3" NAME="L790">SYNOPSIS</A>
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<DL>
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<DD><B>package forget ?</B><I>package package ...</I>?
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<DD><B>package ifneeded </B><I>package version</I> ?<I>script</I>?
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<DD><B>package names</B>
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<DD><B>package present </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?
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<DD><B>package provide </B><I>package </I>?<I>version</I>?
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<DD><B>package require </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?
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<DD><B>package unknown </B>?<I>command</I>?
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<DD><B>package vcompare </B><I>version1 version2</I>
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<DD><B>package versions </B><I>package</I>
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<DD><B>package vsatisfies </B><I>version1 version2</I>
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</DL>
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<DD><A HREF="package.htm#M4" NAME="L791">DESCRIPTION</A>
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<DL>
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<DD><A HREF="package.htm#M5" NAME="L792"><B>package forget ?</B><I>package package ...</I>?</A>
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<DD><A HREF="package.htm#M6" NAME="L793"><B>package ifneeded </B><I>package version</I> ?<I>script</I>?</A>
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<DD><A HREF="package.htm#M7" NAME="L794"><B>package names</B></A>
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<DD><A HREF="package.htm#M8" NAME="L795"><B>package present </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?</A>
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<DD><A HREF="package.htm#M9" NAME="L796"><B>package provide </B><I>package </I>?<I>version</I>?</A>
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<DD><A HREF="package.htm#M10" NAME="L797"><B>package require </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?</A>
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<DD><A HREF="package.htm#M11" NAME="L798"><B>package unknown </B>?<I>command</I>?</A>
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<DD><A HREF="package.htm#M12" NAME="L799"><B>package vcompare </B><I>version1 version2</I></A>
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<DD><A HREF="package.htm#M13" NAME="L800"><B>package versions </B><I>package</I></A>
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<DD><A HREF="package.htm#M14" NAME="L801"><B>package vsatisfies </B><I>version1 version2</I></A>
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</DL>
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<DD><A HREF="package.htm#M15" NAME="L802">VERSION NUMBERS</A>
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<DD><A HREF="package.htm#M16" NAME="L803">PACKAGE INDICES</A>
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<DD><A HREF="package.htm#M17" NAME="L804">SEE ALSO</A>
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<DD><A HREF="package.htm#M18" NAME="L805">KEYWORDS</A>
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</DL><HR>
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<H3><A NAME="M2">NAME</A></H3>
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package - Facilities for package loading and version control
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<H3><A NAME="M3">SYNOPSIS</A></H3>
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<B>package forget ?</B><I>package package ...</I>?<BR>
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<B>package ifneeded </B><I>package version</I> ?<I>script</I>?<BR>
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<B>package names</B><BR>
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<B>package present </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?<BR>
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<B>package provide </B><I>package </I>?<I>version</I>?<BR>
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<B>package require </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?<BR>
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<B>package unknown </B>?<I>command</I>?<BR>
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<B>package vcompare </B><I>version1 version2</I><BR>
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<B>package versions </B><I>package</I><BR>
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<B>package vsatisfies </B><I>version1 version2</I><BR>
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<H3><A NAME="M4">DESCRIPTION</A></H3>
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This command keeps a simple database of the packages available for
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use by the current interpreter and how to load them into the
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interpreter.
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It supports multiple versions of each package and arranges
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for the correct version of a package to be loaded based on what
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is needed by the application.
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This command also detects and reports version clashes.
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Typically, only the <B>package require</B> and <B>package provide</B>
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commands are invoked in normal Tcl scripts; the other commands are used
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primarily by system scripts that maintain the package database.
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<P>
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The behavior of the <B>package</B> command is determined by its first argument.
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The following forms are permitted:
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<P>
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<DL>
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<P><DT><A NAME="M5"><B>package forget ?</B><I>package package ...</I>?</A><DD>
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Removes all information about each specified package from this interpreter,
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including information provided by both <B>package ifneeded</B> and
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<B>package provide</B>.
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<P><DT><A NAME="M6"><B>package ifneeded </B><I>package version</I> ?<I>script</I>?</A><DD>
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This command typically appears only in system configuration
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scripts to set up the package database.
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It indicates that a particular version of
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a particular package is available if needed, and that the package
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can be added to the interpreter by executing <I>script</I>.
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The script is saved in a database for use by subsequent
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<B>package require</B> commands; typically, <I>script</I>
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sets up auto-loading for the commands in the package (or calls
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<B><A HREF="../TkCmd/load.htm">load</A></B> and/or <B><A HREF="../TkCmd/source.htm">source</A></B> directly), then invokes
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<B>package provide</B> to indicate that the package is present.
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There may be information in the database for several different
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versions of a single package.
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If the database already contains information for <I>package</I>
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and <I>version</I>, the new <I>script</I> replaces the existing
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one.
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If the <I>script</I> argument is omitted, the current script for
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version <I>version</I> of package <I>package</I> is returned,
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or an empty string if no <B>package ifneeded</B> command has
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been invoked for this <I>package</I> and <I>version</I>.
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<P><DT><A NAME="M7"><B>package names</B></A><DD>
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Returns a list of the names of all packages in the
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interpreter for which a version has been provided (via
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<B>package provide</B>) or for which a <B>package ifneeded</B>
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script is available.
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The order of elements in the list is arbitrary.
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<P><DT><A NAME="M8"><B>package present </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?</A><DD>
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This command is equivalent to <B>package require</B> except that it
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does not try and load the package if it is not already loaded.
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<P><DT><A NAME="M9"><B>package provide </B><I>package </I>?<I>version</I>?</A><DD>
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This command is invoked to indicate that version <I>version</I>
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of package <I>package</I> is now present in the interpreter.
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It is typically invoked once as part of an <B>ifneeded</B> script,
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and again by the package itself when it is finally loaded.
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An error occurs if a different version of <I>package</I> has been
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provided by a previous <B>package provide</B> command.
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If the <I>version</I> argument is omitted, then the command
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returns the version number that is currently provided, or an
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empty string if no <B>package provide</B> command has been
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invoked for <I>package</I> in this interpreter.
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<P><DT><A NAME="M10"><B>package require </B>?<B>-exact</B>? <I>package </I>?<I>version</I>?</A><DD>
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This command is typically invoked by Tcl code that wishes to use
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a particular version of a particular package. The arguments
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indicate which package is wanted, and the command ensures that
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a suitable version of the package is loaded into the interpreter.
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If the command succeeds, it returns the version number that is
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loaded; otherwise it generates an error.
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If both the <B>-exact</B>
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switch and the <I>version</I> argument are specified then only the
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given version is acceptable. If <B>-exact</B> is omitted but
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<I>version</I> is specified, then versions later than <I>version</I>
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are also acceptable as long as they have the same major version
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number as <I>version</I>.
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If both <B>-exact</B> and <I>version</I> are omitted then any
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version whatsoever is acceptable.
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If a version of <I>package</I> has already been provided (by invoking
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the <B>package provide</B> command), then its version number must
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satisfy the criteria given by <B>-exact</B> and <I>version</I> and
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the command returns immediately.
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Otherwise, the command searches the database of information provided by
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previous <B>package ifneeded</B> commands to see if an acceptable
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version of the package is available.
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If so, the script for the highest acceptable version number is invoked;
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it must do whatever is necessary to load the package,
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including calling <B>package provide</B> for the package.
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If the <B>package ifneeded</B> database does not contain an acceptable
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version of the package and a <B>package unknown</B> command has been
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specified for the interpreter then that command is invoked; when
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it completes, Tcl checks again to see if the package is now provided
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or if there is a <B>package ifneeded</B> script for it.
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If all of these steps fail to provide an acceptable version of the
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package, then the command returns an error.
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<P><DT><A NAME="M11"><B>package unknown </B>?<I>command</I>?</A><DD>
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This command supplies a ``last resort'' command to invoke during
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<B>package require</B> if no suitable version of a package can be found
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in the <B>package ifneeded</B> database.
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If the <I>command</I> argument is supplied, it contains the first part
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of a command; when the command is invoked during a <B>package require</B>
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command, Tcl appends two additional arguments giving the desired package
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name and version.
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For example, if <I>command</I> is <B>foo bar</B> and later the command
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<B>package require test 2.4</B> is invoked, then Tcl will execute
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the command <B>foo bar test 2.4</B> to load the package.
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If no version number is supplied to the <B>package require</B> command,
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then the version argument for the invoked command will be an empty string.
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If the <B>package unknown</B> command is invoked without a <I>command</I>
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argument, then the current <B>package unknown</B> script is returned,
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or an empty string if there is none.
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If <I>command</I> is specified as an empty string, then the current
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<B>package unknown</B> script is removed, if there is one.
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<P><DT><A NAME="M12"><B>package vcompare </B><I>version1 version2</I></A><DD>
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Compares the two version numbers given by <I>version1</I> and <I>version2</I>.
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Returns -1 if <I>version1</I> is an earlier version than <I>version2</I>,
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0 if they are equal, and 1 if <I>version1</I> is later than <B>version2</B>.
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<P><DT><A NAME="M13"><B>package versions </B><I>package</I></A><DD>
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Returns a list of all the version numbers of <I>package</I>
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for which information has been provided by <B>package ifneeded</B>
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commands.
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<P><DT><A NAME="M14"><B>package vsatisfies </B><I>version1 version2</I></A><DD>
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Returns 1 if scripts written for <I>version2</I> will work unchanged
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with <I>version1</I> (i.e. <I>version1</I> is equal to or greater
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than <I>version2</I> and they both have the same major version
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number), 0 otherwise.
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<P></DL>
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<H3><A NAME="M15">VERSION NUMBERS</A></H3>
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Version numbers consist of one or more decimal numbers separated
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by dots, such as 2 or 1.162 or 3.1.13.1.
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The first number is called the major version number.
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Larger numbers correspond to later versions of a package, with
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leftmost numbers having greater significance.
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For example, version 2.1 is later than 1.3 and version
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3.4.6 is later than 3.3.5.
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Missing fields are equivalent to zeroes: version 1.3 is the
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same as version 1.3.0 and 1.3.0.0, so it is earlier than 1.3.1 or 1.3.0.2.
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A later version number is assumed to be upwards compatible with
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an earlier version number as long as both versions have the same
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major version number.
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For example, Tcl scripts written for version 2.3 of a package should
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work unchanged under versions 2.3.2, 2.4, and 2.5.1.
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Changes in the major version number signify incompatible changes:
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if code is written to use version 2.1 of a package, it is not guaranteed
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to work unmodified with either version 1.7.3 or version 3.1.
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<H3><A NAME="M16">PACKAGE INDICES</A></H3>
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The recommended way to use packages in Tcl is to invoke <B>package require</B>
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and <B>package provide</B> commands in scripts, and use the procedure
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<B>pkg_mkIndex</B> to create package index files.
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Once you've done this, packages will be loaded automatically
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in response to <B>package require</B> commands.
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See the documentation for <B>pkg_mkIndex</B> for details.
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<H3><A NAME="M17">SEE ALSO</A></H3>
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<B><A HREF="../TkCmd/msgcat.htm">msgcat</A></B>, <B>packagens</B>, <B>pkgMkIndex</B>
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<H3><A NAME="M18">KEYWORDS</A></H3>
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<A href="../Keywords/P.htm#package">package</A>, <A href="../Keywords/V.htm#version">version</A>
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<HR><PRE>
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<A HREF="../copyright.htm">Copyright</A> © 1996 Sun Microsystems, Inc.
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<A HREF="../copyright.htm">Copyright</A> © 1995-1997 Roger E. Critchlow Jr.</PRE>
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</BODY></HTML>
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