variable(n)

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NAME

       variable - create and initialize a namespace variable

SYNOPSIS

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

       This command is normally used within a namespace eval command to create
       one or more variables within a namespace.  Each variable name  is  ini-
       tialized with value.  The value for the last variable is optional.

       If  a  variable  name  does not exist, it is created.  In this case, if
       value is specified, it is assigned to the newly created  variable.   If
       no  value  is  specified,  the  new variable is left undefined.  If the
       variable already exists, it is set to value if value  is  specified  or
       left  unchanged  if  no  value is given.  Normally, name is unqualified
       (does not include the names of  any  containing  namespaces),  and  the
       variable  is  created  in  the current namespace.  If name includes any
       namespace qualifiers, the variable is created in the  specified  names-
       pace.  If the variable is not defined, it will be visible to the names-
       pace which command, but not to the info exists command.

       If the variable command is executed inside a Tcl procedure, it  creates
       local  variables  linked  to the corresponding namespace variables (and
       therefore these variables are listed by info vars.)  In  this  way  the
       variable command resembles the global command, although the global com-
       mand only links to variables in the global namespace.   If  any  values
       are  given, they are used to modify the values of the associated names-
       pace variables.  If a namespace variable does not exist, it is  created
       and optionally initialized.

       A  name argument cannot reference an element within an array.  Instead,
       name should reference the entire array, and  the  initialization  value
       should  be  left  off.   After the variable has been declared, elements
       within the array can be set using ordinary set or array commands.

EXAMPLES

       Create a variable in a namespace:
              namespace eval foo {
                  variable bar 12345
              }

       Create an array in a namespace:
              namespace eval someNS {
                  variable someAry
                  array set someAry {
                      someName  someValue
                      otherName otherValue
                  }
              }

       Access variables in namespaces from a procedure:
              namespace eval foo {
                  proc spong {} {
                      # Variable in this namespace
                      variable bar
                      puts "bar is $bar"

                      # Variable in another namespace
                      variable ::someNS::someAry
                      parray someAry
                  }
              }

SEE ALSO

       global(n), namespace(n), upvar(n)

KEYWORDS

       global, namespace, procedure, variable

Tcl                                   8.0                          variable(n)