NAME

       code - capture the namespace context for a code fragment

SYNOPSIS

       itcl::code ?-namespace name? command ?arg arg ...?

DESCRIPTION

       Creates  a  scoped  value  for  the specified command and its associated arg arguments.  A
       scoped value is a list with three elements:  the "@scope" keyword,  a  namespace  context,
       and a value string.  For example, the command namespace foo {
           code  puts  "Hello  World!"   }  produces  the scoped value: @scope ::foo {puts {Hello
       World!}} Note that the code command  captures  the  current  namespace  context.   If  the
       -namespace  flag is specified, then the current context is ignored, and the name string is
       used as the namespace context.

       Extensions like Tk execute ordinary code fragments in  the  global  namespace.   A  scoped
       value captures a code fragment together with its namespace context in a way that allows it
       to be executed properly later.  It is needed, for example, to wrap up code fragments  when
       a Tk widget is used within a namespace: namespace foo {
           private proc report {mesg} {
               puts "click: $mesg"
           }

           button .b1 -text "Push Me"         -command [code report "Hello World!"]
           pack  .b1  }  The  code  fragment  associated  with button .b1 only makes sense in the
       context of namespace "foo".  Furthermore, the "report" procedure is private, and can  only
       be  accessed  within that namespace.  The code command wraps up the code fragment in a way
       that allows it to be executed properly when the button is pressed.

       Also, note that the code command preserves the integrity of arguments on the command line.
       This  makes  it  a natural replacement for the list command, which is often used to format
       Tcl code fragments.  In other words, instead of using the list command  like  this:  after
       1000  [list  puts  "Hello  $name!"]  use the code command like this: after 1000 [code puts
       "Hello $name!"]  This not only formats  the  command  correctly,  but  also  captures  its
       namespace context.

       Scoped  commands  can  be  invoked  like ordinary code fragments, with or without the eval
       command.  For example, the following statements work properly: set cmd {@scope ::foo  .b1}
       $cmd configure -background red

       set  opts {-bg blue -fg white} eval $cmd configure $opts Note that scoped commands by-pass
       the usual protection mechanisms; the command: @scope ::foo {report {Hello World!}} can  be
       used  to  access  the  "foo::report"  proc  from  any namespace context, even though it is
       private.

KEYWORDS

       scope, callback, namespace, public, protected, private