NAME

       scope - capture the namespace context for a variable

SYNOPSIS

       itcl::scope name

DESCRIPTION

       Creates a scoped value for the specified name, which must be a variable name.  If the name
       is an instance variable, then the scope command returns a string of  the  following  form:
       @itcl  object  varName This is recognized in any context as an instance variable belonging
       to object.  So with itcl3.0 and beyond, it  is  possible  to  use  instance  variables  in
       conjunction  with  widgets.  For example, if you have an object with a private variable x,
       and you can use x in conjunction with the -textvariable option of an entry widget.  Before
       itcl3.0, only common variables could be used in this manner.

       If  the  name  is  not an instance variable, then it must be a common variable or a global
       variable.  In that case, the scope  command  returns  the  fully  qualified  name  of  the
       variable, e.g., ::foo::bar::x.

       If the name is not recognized as a variable, the scope command returns an error.

       Ordinary  variable  names  refer  to  variables  in  the global namespace.  A scoped value
       captures a variable name together with its namespace context in a way that allows it to be
       referenced properly later.  It is needed, for example, to wrap up variable names when a Tk
       widget is used within a namespace: namespace foo {
           private variable mode 1

           radiobutton .rb1 -text "Mode #1"         -variable [scope mode] -value 1
           pack .rb1

           radiobutton .rb2 -text "Mode #2"         -variable [scope mode] -value 2
           pack .rb2 } Radiobuttons .rb1 and .rb2 interact via the variable "mode"  contained  in
       the  namespace  "foo".  The scope command guarantees this by returning the fully qualified
       variable name ::foo::mode.

       You should never use the @itcl syntax directly.  For example, it is a bad  idea  to  write
       code  like  this:  set  {@itcl  ::fred  x} 3 puts "value = ${@itcl ::fred x}" Instead, you
       should always use the scope command to generate the variable name dynamically.  Then,  you
       can pass that name to a widget or to any other bit of code in your program.

KEYWORDS

       code, namespace, variable