1variable(n)                  Tcl Built-In Commands                 variable(n)
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NAME

8       variable - create and initialize a namespace variable
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SYNOPSIS

11       variable ?name value...? name ?value?
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DESCRIPTION

16       This command is normally used within a namespace eval command to create
17       one or more variables within a namespace.  Each variable name  is  ini‐
18       tialized with value.  The value for the last variable is optional.
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20       If  a  variable  name  does not exist, it is created.  In this case, if
21       value is specified, it is assigned to the newly created  variable.   If
22       no  value  is  specified,  the  new variable is left undefined.  If the
23       variable already exists, it is set to value if value  is  specified  or
24       left  unchanged  if  no  value is given.  Normally, name is unqualified
25       (does not include the names of  any  containing  namespaces),  and  the
26       variable  is  created  in  the current namespace.  If name includes any
27       namespace qualifiers, the variable is created in the  specified  names‐
28       pace.  If the variable is not defined, it will be visible to the names‐
29       pace which command, but not to the info exists command.
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31       If the variable command is executed inside a Tcl procedure, it  creates
32       local  variables  linked  to the corresponding namespace variables (and
33       therefore these variables are listed by info vars.)  In  this  way  the
34       variable command resembles the global command, although the global com‐
35       mand only links to variables in the global namespace.   If  any  values
36       are  given, they are used to modify the values of the associated names‐
37       pace variables.  If a namespace variable does not exist, it is  created
38       and optionally initialized.
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40       A  name argument cannot reference an element within an array.  Instead,
41       name should reference the entire array, and  the  initialization  value
42       should  be  left  off.   After the variable has been declared, elements
43       within the array can be set using ordinary set or array commands.
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EXAMPLES

46       Create a variable in a namespace:
47              namespace eval foo {
48                  variable bar 12345
49              }
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51       Create an array in a namespace:
52              namespace eval someNS {
53                  variable someAry
54                  array set someAry {
55                      someName  someValue
56                      otherName otherValue
57                  }
58              }
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60       Access variables in namespaces from a procedure:
61              namespace eval foo {
62                  proc spong {} {
63                      # Variable in this namespace
64                      variable bar
65                      puts "bar is $bar"
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67                      # Variable in another namespace
68                      variable ::someNS::someAry
69                      parray someAry
70                  }
71              }
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SEE ALSO

75       global(n), namespace(n), upvar(n)
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KEYWORDS

79       global, namespace, procedure, variable
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83Tcl                                   8.0                          variable(n)