106 lines
3.1 KiB
Plaintext
106 lines
3.1 KiB
Plaintext
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'\"
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'\" Copyright (c) 1993-1997 Bell Labs Innovations for Lucent Technologies
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'\" Copyright (c) 1997 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH variable n 8.0 Tcl "Tcl Built-In Commands"
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.so man.macros
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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variable \- create and initialize a namespace variable
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.SH SYNOPSIS
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\fBvariable \fR\fIname\fR
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.sp
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\fBvariable \fR?\fIname value...\fR?
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.BE
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.SH DESCRIPTION
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.PP
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This command is normally used within a
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\fBnamespace eval\fR command to create one or more variables
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within a namespace.
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Each variable \fIname\fR is initialized with \fIvalue\fR.
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The \fIvalue\fR for the last variable is optional.
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.PP
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If a variable \fIname\fR does not exist, it is created.
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In this case, if \fIvalue\fR is specified,
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it is assigned to the newly created variable.
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If no \fIvalue\fR 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 \fIvalue\fR if \fIvalue\fR is specified
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or left unchanged if no \fIvalue\fR is given.
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Normally, \fIname\fR 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 \fIname\fR 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 \fBnamespace which\fR
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command, but not to the \fBinfo exists\fR command.
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.PP
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If the \fBvariable\fR 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 \fBinfo vars\fR.)
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In this way the \fBvariable\fR command resembles the \fBglobal\fR command,
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although the \fBglobal\fR command
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resolves variable names with respect to the global namespace instead
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of the current namespace of the procedure.
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If any \fIvalue\fRs 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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.PP
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A \fIname\fR argument cannot reference an element within an array.
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Instead, \fIname\fR should reference the entire array,
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and the initialization \fIvalue\fR 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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\fBset\fR or \fBarray\fR commands.
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.SH EXAMPLES
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.PP
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Create a variable in a namespace:
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.PP
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.CS
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namespace eval foo {
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\fBvariable\fR bar 12345
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}
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.CE
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.PP
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Create an array in a namespace:
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.PP
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.CS
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namespace eval someNS {
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\fBvariable\fR someAry
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array set someAry {
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someName someValue
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otherName otherValue
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}
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}
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.CE
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.PP
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Access variables in namespaces from a procedure:
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.PP
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.CS
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namespace eval foo {
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proc spong {} {
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# Variable in this namespace
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\fBvariable\fR bar
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puts "bar is $bar"
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# Variable in another namespace
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\fBvariable\fR ::someNS::someAry
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parray someAry
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}
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}
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.CE
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.SH "SEE ALSO"
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global(n), namespace(n), upvar(n)
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.SH KEYWORDS
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global, namespace, procedure, variable
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.\" Local variables:
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.\" mode: nroff
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.\" fill-column: 78
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.\" End:
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