plucky (3) variable.3tcl.gz

NAME

       variable - create and initialize a namespace variable

SYNOPSIS

       variable name

       variable ?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 initialized 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  namespace.  If the variable is not defined, it will be visible to the namespace 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 command  resolves  variable  names
       with  respect  to  the global namespace instead of the current namespace of the procedure.  If any values
       are given, they are used to modify the values of the associated  namespace  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(3tcl), namespace(3tcl), upvar(3tcl)

KEYWORDS

       global, namespace, procedure, variable