body(n)                           [incr Tcl]                           body(n)



NAME
       body - change the body for a class method/proc

SYNOPSIS
       body className::::function args body


DESCRIPTION
       The  body  command is used outside of an [incr Tcl] class definition to
       define or redefine the body of a class method or proc.   This  facility
       allows a class definition to have separate "interface" and "implementa-
       tion" parts.  The "interface" part is a class command with declarations
       for  methods,  procs,  instance  variables  and  common variables.  The
       "implementation" part is a series of body and configbody commands.   If
       the "implementation" part is kept in a separate file, it can be sourced
       again and again as bugs are fixed, to support interactive  development.
       When  using  the  "tcl"  mode  in the emacs editor, the "interface" and
       "implementation" parts can be kept in the same file; as bugs are fixed,
       individual  bodies can be highlighted and sent to the test application.

       The  name  "className::::function"  identifies  the   method/proc   being
       changed.

       If  an  args  list  was  specified when the function was defined in the
       class definition, the args list for the  body  command  must  match  in
       meaning.   Variable  names can change, but the argument lists must have
       the same required arguments and the same default  values  for  optional
       arguments.   The special args argument acts as a wildcard when included
       in the args list in the class definition; it will match  zero  or  more
       arguments of any type when the body is redefined.

       If  the body string starts with "@@", it is treated as the symbolic name
       for a C procedure.  The args list has little meaning for the  C  proce-
       dure,  except  to document the expected usage.  (The C procedure is not
       guaranteed to use arguments in this manner.)  If body  does  not  start
       with  "@@", it is treated as a Tcl command script.  When the function is
       invoked, command line arguments are matched against the args list,  and
       local  variables  are  created to represent each argument.  This is the
       usual behavior for a Tcl-style proc.

       Symbolic names for C procedures are established by  registering  proce-
       dures  via ItclRegisterC().  This is usually done in the TclAppInit()
       procedure, which is automatically called when  the  interpreter  starts
       up.   In the following example, the procedure MyFooCmd() is registered
       with the symbolic name "foo".  This procedure can be referenced in  the
       body command as "@foo".  int TclAppInit(interp)
           TclInterp *interp;     /* Interpreter for application. */ {
           if (ItclInit(interp) == TCLEROR) {
               return TCLEROR;
           }

           if (ItclRegisterC(interp, "foo", MyFooCmd) != TCLOK) {
               return TCLEROR;
           } }


EXAMPLE
       In  the  following example, a "File" class is defined to represent open
       files.  The method bodies are included below the class  definition  via
       the  body  command.  Note that the bodies of the constructor/destructor
       must be included in the class definition, but they can be redefined via
       the body command as well.  class File {
           private variable fid ""
           constructor {name access} {
               set fid [open $name $access]
           }
           destructor {
               close $fid
           }

           method get {}
           method put {line}
           method eof {} }

       body File::get {} {
           return [gets $fid] } body File::put {line} {
           puts $fid $line } body File::eof {} {
           return [::eof $fid] }

       #  #  See the File class in action: # File x /etc/passwd "r" while {![x
       eof]} {
           puts "=> [x get]" } delete object x


KEYWORDS
       class, object, procedure



itcl                                  3.0                              body(n)