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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
       "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  behav-ior behavior
       ior 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 construc-tor/destructor constructor/destructor
       tor/destructor must be included in the class definition, but they can be redefined via the body  com-mand command
       mand 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)