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RedHat 9 (Linux i386) - man page for code (redhat section n)

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code(n) 				    [incr Tcl]					  code(n)

       code - capture the namespace context for a code fragment

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

       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 con-
       text 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 names-
       pace context.

       Scoped commands can be invoked like ordinary code fragments, with or without the eval com-
       mand.  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 pri-

       scope, callback, namespace, public, protected, private

itcl					       3.0					  code(n)
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