1body(n)                           [incr Tcl]                           body(n)
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NAME

8       body - change the body for a class method/proc
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SYNOPSIS

11       itcl::body className::function args body
12_________________________________________________________________
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DESCRIPTION

16       The  body  command is used outside of an [incr Tcl] class definition to
17       define or redefine the body of a class method or proc.   This  facility
18       allows a class definition to have separate "interface" and "implementa‐
19       tion" parts.  The "interface" part is a class command with declarations
20       for  methods,  procs,  instance  variables  and  common variables.  The
21       "implementation" part is a series of body and configbody commands.   If
22       the "implementation" part is kept in a separate file, it can be sourced
23       again and again as bugs are fixed, to support interactive  development.
24       When  using  the  "tcl"  mode  in the emacs editor, the "interface" and
25       "implementation" parts can be kept in the same file; as bugs are fixed,
26       individual bodies can be highlighted and sent to the test application.
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28       The   name   "className::function"  identifies  the  method/proc  being
29       changed.
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31       If an args list was specified when the  function  was  defined  in  the
32       class  definition,  the  args  list  for the body command must match in
33       meaning.  Variable names can change, but the argument lists  must  have
34       the  same  required  arguments and the same default values for optional
35       arguments.  The special args argument acts as a wildcard when  included
36       in  the  args  list in the class definition; it will match zero or more
37       arguments of any type when the body is redefined.
38
39       If the body string starts with "@", it is treated as the symbolic  name
40       for  a  C procedure.  The args list has little meaning for the C proce‐
41       dure, except to document the expected usage.  (The C procedure  is  not
42       guaranteed  to  use  arguments in this manner.)  If body does not start
43       with "@", it is treated as a Tcl command script.  When the function  is
44       invoked,  command line arguments are matched against the args list, and
45       local variables are created to represent each argument.   This  is  the
46       usual behavior for a Tcl-style proc.
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48       Symbolic  names  for C procedures are established by registering proce‐
49       dures via Itcl_RegisterC().  This is usually done in the  Tcl_AppInit()
50       procedure,  which  is  automatically called when the interpreter starts
51       up.  In the following example, the procedure My_FooCmd() is  registered
52       with  the symbolic name "foo".  This procedure can be referenced in the
53       body command as "@foo".
54              int
55              Tcl_AppInit(interp)
56                  Tcl_Interp *interp;     /* Interpreter for application. */
57              {
58                  if (Itcl_Init(interp) == TCL_ERROR) {
59                      return TCL_ERROR;
60                  }
61
62                  if (Itcl_RegisterC(interp, "foo", My_FooCmd) != TCL_OK) {
63                      return TCL_ERROR;
64                  }
65              }
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67

EXAMPLE

69       In the following example, a "File" class is defined to  represent  open
70       files.   The  method bodies are included below the class definition via
71       the body command.  Note that the bodies of  the  constructor/destructor
72       must be included in the class definition, but they can be redefined via
73       the body command as well.
74              itcl::class File {
75                  private variable fid ""
76                  constructor {name access} {
77                      set fid [open $name $access]
78                  }
79                  destructor {
80                      close $fid
81                  }
82
83                  method get {}
84                  method put {line}
85                  method eof {}
86              }
87
88              itcl::body File::get {} {
89                  return [gets $fid]
90              }
91              itcl::body File::put {line} {
92                  puts $fid $line
93              }
94              itcl::body File::eof {} {
95                  return [::eof $fid]
96              }
97
98              #
99              # See the File class in action:
100              #
101              File x /etc/passwd "r"
102              while {![x eof]} {
103                  puts "=> [x get]"
104              }
105              itcl::delete object x
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KEYWORDS

109       class, object, procedure
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113itcl                                  3.0                              body(n)
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