'\"
'\" Copyright (c) 1993-1998  Lucent Technologies, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
'\" RCS: $Id: configbody.n,v 1.2 1999/01/27 18:56:04 jingham Exp $
'\"
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
'\"	or "in/out" to describe whether procedure reads or modifies arg,
'\"	and indent is equivalent to second arg of .IP (shouldn't ever be
'\"	needed;  use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\"	Give maximum sizes of arguments for setting tab stops.  Type and
'\"	name are examples of largest possible arguments that will be passed
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'\"
'\" .BS
'\"	Start box enclosure.  From here until next .BE, everything will be
'\"	enclosed in one large box.
'\"
'\" .BE
'\"	End of box enclosure.
'\"
'\" .CS
'\"	Begin code excerpt.
'\"
'\" .CE
'\"	End code excerpt.
'\"
'\" .VS ?version? ?br?
'\"	Begin vertical sidebar, for use in marking newly-changed parts
'\"	of man pages.  The first argument is ignored and used for recording
'\"	the version when the .VS was added, so that the sidebars can be
'\"	found and removed when they reach a certain age.  If another argument
'\"	is present, then a line break is forced before starting the sidebar.
'\"
'\" .VE
'\"	End of vertical sidebar.
'\"
'\" .DS
'\"	Begin an indented unfilled display.
'\"
'\" .DE
'\"	End of indented unfilled display.
'\"
'\" .SO
'\"	Start of list of standard options for a Tk widget.  The
'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
'\"
'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\"	Start of description of a specific option.  cmdName gives the
'\"	option's name as specified in the class command, dbName gives
'\"	the option's name in the option database, and dbClass gives
'\"	the option's class in the option database.
'\"
'\" .UL arg1 arg2
'\"	Print arg1 underlined, then print arg2 normally.
'\"
'\" SCCS: @(#) man.macros 1.9 97/08/22 18:50:59
'\"
'\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
'\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ie !"\\$3"" \{\
.ta \\n()Au \\n()Bu
\&\\$1	\\fI\\$2\\fP	(\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
'\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
'\"	# BS - start boxed text
'\"	# ^y = starting y location
'\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
'\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
'\"	# VS - start vertical sidebar
'\"	# ^Y = starting y location
'\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
'\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
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\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
'\"	# Special macro to handle page bottom:  finish off current
'\"	# box/sidebar if in box/sidebar mode, then invoked standard
'\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
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.ev
.if \\n(^b \{\
.mk ^y
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.if \\n(^v \{\
.mk ^Y
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..
'\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
'\"	# DE - end display
.de DE
.fi
.RE
.sp
..
'\"	# SO - start of list of standard options
.de SO
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 4c 8c 12c
.ft B
..
'\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\fBoptions\\fR manual entry for details on the standard options.
..
'\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
'\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
'\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.de UL
\\$1\l'|0\(ul'\\$2
..
.TH configbody n 3.0 itcl "[incr\ Tcl]"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
configbody \- change the "config" code for a public variable
.SH SYNOPSIS
\fBconfigbody \fIclassName\fB::\fIvarName body\fR
.BE

.SH DESCRIPTION
.PP
The \fBconfigbody\fR command is used outside of an \fB[incr\ Tcl]\fR
class definition to define or redefine the configuration code
associated with a public variable.  Public variables act like
configuration options for an object.  They can be modified
outside the class scope using the built-in \fBconfigure\fR method.
Each variable can have a bit of "config" code associate with it
that is automatically executed when the variable is configured.
The \fBconfigbody\fR command can be used to define or redefine
this body of code.
.PP
Like the \fBbody\fR command, this facility allows a class definition
to have separate "interface" and "implementation" parts.
The "interface" part is a \fBclass\fR command with declarations
for methods, procs, instance variables and common variables.
The "implementation" part is a series of \fBbody\fR and
\fBconfigbody\fR 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 \fBemacs\fR 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.
.PP
The name "\fIclassName\fB::\fIvarName\fR"
identifies the public variable being updated.
If the \fIbody\fR string starts with "\fB@\fR", it is treated
as the symbolic name for a C procedure.  Otherwise, it is
treated as a Tcl command script.
.PP
Symbolic names for C procedures are established by registering
procedures via \fBItcl_RegisterC()\fR.  This is usually done
in the \fBTcl_AppInit()\fR procedure, which is automatically called
when the interpreter starts up.  In the following example,
the procedure \fCMy_FooCmd()\fR is registered with the
symbolic name "foo".  This procedure can be referenced in
the \fBconfigbody\fR command as "\fC@foo\fR".
.CS
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;
    }
}
.CE

.SH EXAMPLE
In the following example, a "File" class is defined to represent
open files.  Whenever the "-name" option is configured, the
existing file is closed, and a new file is opened.  Note that
the "config" code for a public variable is optional.  The "-access"
option, for example, does not have it.
.CS
class File {
    private variable fid ""

    public variable name ""
    public variable access "r"

    constructor {args} {
        eval configure $args
    }
    destructor {
        if {$fid != ""} {
            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]
}

configbody File::name {
    if {$fid != ""} {
        close $fid
    }
    set fid [open $name $access]
}

#
# See the File class in action:
#
File x

x configure -name /etc/passwd
while {![x eof]} {
    puts "=> [x get]"
}
delete object x
.CE

.SH KEYWORDS
class, object, variable, configure
