'\"
|
'\"
|
'\" Copyright (c) 1993-1998 Lucent Technologies, Inc.
|
'\" Copyright (c) 1993-1998 Lucent Technologies, Inc.
|
'\"
|
'\"
|
'\" See the file "license.terms" for information on usage and redistribution
|
'\" See the file "license.terms" for information on usage and redistribution
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
'\"
|
'\"
|
'\" RCS: $Id: scope.n,v 1.1.1.1 2002-01-16 10:24:46 markom Exp $
|
'\" RCS: $Id: scope.n,v 1.1.1.1 2002-01-16 10:24:46 markom Exp $
|
'\"
|
'\"
|
.so man.macros
|
.so man.macros
|
.TH scope n "" Tcl "[incr\ Tcl]"
|
.TH scope n "" Tcl "[incr\ Tcl]"
|
.BS
|
.BS
|
'\" Note: do not modify the .SH NAME line immediately below!
|
'\" Note: do not modify the .SH NAME line immediately below!
|
.SH NAME
|
.SH NAME
|
scope \- capture the namespace context for a variable
|
scope \- capture the namespace context for a variable
|
.SH SYNOPSIS
|
.SH SYNOPSIS
|
\fBscope \fIname\fR
|
\fBscope \fIname\fR
|
.BE
|
.BE
|
|
|
.SH DESCRIPTION
|
.SH DESCRIPTION
|
.PP
|
.PP
|
Creates a scoped value for the specified \fIname\fR, which must
|
Creates a scoped value for the specified \fIname\fR, which must
|
be a variable name. If the \fIname\fR is an instance variable,
|
be a variable name. If the \fIname\fR is an instance variable,
|
then the scope command returns a string of the following form:
|
then the scope command returns a string of the following form:
|
.CS
|
.CS
|
@itcl \fIobject varName\fP
|
@itcl \fIobject varName\fP
|
.CE
|
.CE
|
This is recognized in any context as an instance variable belonging
|
This is recognized in any context as an instance variable belonging
|
to \fIobject\fR. So with itcl3.0 and beyond, it is possible to use
|
to \fIobject\fR. So with itcl3.0 and beyond, it is possible to use
|
instance variables in conjunction with widgets. For example, if you
|
instance variables in conjunction with widgets. For example, if you
|
have an object with a private variable \fCx\fR, and you can use
|
have an object with a private variable \fCx\fR, and you can use
|
\fCx\fR in conjunction with the \fC-textvariable\fR option of an
|
\fCx\fR in conjunction with the \fC-textvariable\fR option of an
|
entry widget. Before itcl3.0, only common variables could be used
|
entry widget. Before itcl3.0, only common variables could be used
|
in this manner.
|
in this manner.
|
.PP
|
.PP
|
If the \fIname\fR is not an instance variable, then it must be
|
If the \fIname\fR is not an instance variable, then it must be
|
a common variable or a global variable. In that case, the scope
|
a common variable or a global variable. In that case, the scope
|
command returns the fully qualified name of the variable, e.g.,
|
command returns the fully qualified name of the variable, e.g.,
|
\fC::foo::bar::x\fR.
|
\fC::foo::bar::x\fR.
|
.PP
|
.PP
|
If the \fIname\fR is not recognized as a variable, the scope
|
If the \fIname\fR is not recognized as a variable, the scope
|
command returns an error.
|
command returns an error.
|
.PP
|
.PP
|
Ordinary variable names refer to variables in the global namespace.
|
Ordinary variable names refer to variables in the global namespace.
|
A scoped value captures a variable name together with its namespace
|
A scoped value captures a variable name together with its namespace
|
context in a way that allows it to be referenced properly later.
|
context in a way that allows it to be referenced properly later.
|
It is needed, for example, to wrap up variable names when a Tk
|
It is needed, for example, to wrap up variable names when a Tk
|
widget is used within a namespace:
|
widget is used within a namespace:
|
.CS
|
.CS
|
namespace foo {
|
namespace foo {
|
private variable mode 1
|
private variable mode 1
|
|
|
radiobutton .rb1 -text "Mode #1" \
|
radiobutton .rb1 -text "Mode #1" \
|
-variable [scope mode] -value 1
|
-variable [scope mode] -value 1
|
pack .rb1
|
pack .rb1
|
|
|
radiobutton .rb2 -text "Mode #2" \
|
radiobutton .rb2 -text "Mode #2" \
|
-variable [scope mode] -value 2
|
-variable [scope mode] -value 2
|
pack .rb2
|
pack .rb2
|
}
|
}
|
.CE
|
.CE
|
Radiobuttons \fC.rb1\fR and \fC.rb2\fR interact via the variable
|
Radiobuttons \fC.rb1\fR and \fC.rb2\fR interact via the variable
|
"mode" contained in the namespace "foo". The \fBscope\fR command
|
"mode" contained in the namespace "foo". The \fBscope\fR command
|
guarantees this by returning the fully qualified variable name
|
guarantees this by returning the fully qualified variable name
|
\fC::foo::mode\fR.
|
\fC::foo::mode\fR.
|
.PP
|
.PP
|
You should never use the \fC@itcl\fR syntax directly. For example,
|
You should never use the \fC@itcl\fR syntax directly. For example,
|
it is a bad idea to write code like this:
|
it is a bad idea to write code like this:
|
.CS
|
.CS
|
set {@itcl ::fred x} 3
|
set {@itcl ::fred x} 3
|
puts "value = ${@itcl ::fred x}"
|
puts "value = ${@itcl ::fred x}"
|
.CE
|
.CE
|
Instead, you should always use the scope command to generate the
|
Instead, you should always use the scope command to generate the
|
variable name dynamically. Then, you can pass that name to a widget
|
variable name dynamically. Then, you can pass that name to a widget
|
or to any other bit of code in your program.
|
or to any other bit of code in your program.
|
|
|
.SH KEYWORDS
|
.SH KEYWORDS
|
code, namespace, variable
|
code, namespace, variable
|
|
|
