NAME

       itcl::body - change the body for a class method/proc

SYNOPSIS

       itcl::body className::function args body
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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
       "implementation"  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 procedure, 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 procedures via Itcl_RegisterC().  This  is
       usually  done  in  the Tcl_AppInit() procedure, which is automatically called when the interpreter starts
       up.  In the following example, the procedure My_FooCmd() is registered  with  the  symbolic  name  "foo".
       This procedure can be referenced in the body command as "@foo".
              int
              Tcl_AppInit(interp)
                  Tcl_Interp *interp;     /* Interpreter for application. */
              {
                  if (Itcl_Init(interp) == TCL_ERROR) {
                      return TCL_ERROR;
                  }

                  if (Itcl_RegisterC(interp, "foo", My_FooCmd) != TCL_OK) {
                      return TCL_ERROR;
                  }
              }

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.
              itcl::class File {
                  private variable fid ""
                  constructor {name access} {
                      set fid [open $name $access]
                  }
                  destructor {
                      close $fid
                  }

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

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

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

KEYWORDS

       class, object, procedure

itcl                                                   3.0                                           body(3itcl)