56 lines
3.0 KiB
HTML
56 lines
3.0 KiB
HTML
<HTML><HEAD><TITLE>Tcl Built-In Commands - variable manual page</TITLE></HEAD><BODY>
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<H3><A NAME="M2">NAME</A></H3>
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variable - create and initialize a namespace variable
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<H3><A NAME="M3">SYNOPSIS</A></H3>
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<B>variable </B>?<I>name value...</I>? <I>name </I>?<I>value</I>?<BR>
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<H3><A NAME="M4">DESCRIPTION</A></H3>
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This command is normally used within a
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<B>namespace eval</B> command to create one or more variables
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within a namespace.
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Each variable <I>name</I> is initialized with <I>value</I>.
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The <I>value</I> for the last variable is optional.
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<P>
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If a variable <I>name</I> does not exist, it is created.
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In this case, if <I>value</I> is specified,
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it is assigned to the newly created variable.
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If no <I>value</I> is specified, the new variable is left undefined.
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If the variable already exists,
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it is set to <I>value</I> if <I>value</I> is specified
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or left unchanged if no <I>value</I> is given.
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Normally, <I>name</I> is unqualified
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(does not include the names of any containing namespaces),
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and the variable is created in the current namespace.
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If <I>name</I> includes any namespace qualifiers,
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the variable is created in the specified namespace. If the variable
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is not defined, it will be visible to the <B>namespace which</B>
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command, but not to the <B><A HREF="../TkCmd/info.htm">info exists</A></B> command.
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<P>
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If the <B>variable</B> command is executed inside a Tcl procedure,
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it creates local variables
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linked to the corresponding namespace variables (and therefore these
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variables are listed by <B><A HREF="../TkCmd/info.htm">info locals</A></B>.)
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In this way the <B>variable</B> command resembles the <B><A HREF="../TkCmd/global.htm">global</A></B> command,
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although the <B><A HREF="../TkCmd/global.htm">global</A></B> command
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only links to variables in the global namespace.
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If any <I>value</I>s are given,
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they are used to modify the values of the associated namespace variables.
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If a namespace variable does not exist,
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it is created and optionally initialized.
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<P>
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A <I>name</I> argument cannot reference an element within an array.
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Instead, <I>name</I> should reference the entire array,
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and the initialization <I>value</I> should be left off.
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After the variable has been declared,
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elements within the array can be set using ordinary
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<B><A HREF="../TkCmd/set.htm">set</A></B> or <B><A HREF="../TkCmd/array.htm">array</A></B> commands.
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<H3><A NAME="M5">SEE ALSO</A></H3>
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<B><A HREF="../TkCmd/global.htm">global</A></B>, <B><A HREF="../TkCmd/namespace.htm">namespace</A></B>, <B><A HREF="../TkCmd/upvar.htm">upvar</A></B>
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<H3><A NAME="M6">KEYWORDS</A></H3>
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<A href="../Keywords/G.htm#global">global</A>, <A href="../Keywords/N.htm#namespace">namespace</A>, <A href="../Keywords/P.htm#procedure">procedure</A>, <A href="../Keywords/V.htm#variable">variable</A>
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<HR><PRE>
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<A HREF="../copyright.htm">Copyright</A> © 1993-1997 Bell Labs Innovations for Lucent Technologies
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<A HREF="../copyright.htm">Copyright</A> © 1997 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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