global(3tcl)

NAME

   global - Access global variables

SYNOPSIS

   global varname ?varname ...?
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DESCRIPTION

   This  command  has  no  effect unless executed in the context of a proc
   body.  If the global command is executed in the context of a proc body,
   it creates local variables linked to the corresponding global variables
   (though these linked variables, like those created by  upvar,  are  not
   included in the list returned by info locals).

   If  varname contains namespace qualifiers, the local variable's name is
   the unqualified name of the  global  variable,  as  determined  by  the
   namespace tail command.

   varname  is  always  treated  as  the  name of a variable, not an array
   element.  An error is returned if the name looks like an array element,
   such as a(b).

EXAMPLES

   This procedure sets the namespace variable ::a::x
          proc reset {} {
              global a::x
              set x 0
          }

   This procedure accumulates the strings passed to it in a global buffer,
   separated by newlines.  It is useful for situations when  you  want  to
   build  a  message  piece-by-piece  (as if with puts) but send that full
   message in a single piece (e.g. over a connection opened with socket or
   as part of a counted HTTP response).
          proc accum {string} {
              global accumulator
              append accumulator $string \n
          }

SEE ALSO

   namespace(3tcl), upvar(3tcl), variable(3tcl)

KEYWORDS

   global, namespace, procedure, variable

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