itcl_class.n

这是一个Linux下的集成开发环境

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'\" RCS: $Id: itcl_class.n,v 1.1 2003/02/05 10:53:53 mdejong Exp $
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.so man.macros
.TH itcl_class n 3.0 itcl "[incr\ Tcl]"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
itcl_class \- create a class of objects (obsolete)
.SH SYNOPSIS
\fBitcl_class \fIclassName\fR \fB{
.br
    \fBinherit \fIbaseClass\fR ?\fIbaseClass\fR...?
.br
    \fBconstructor \fIargs\fR ?\fIinit\fR? \fIbody\fR
.br
    \fBdestructor \fIbody\fR
.br
    \fBmethod \fIname args body\fR
.br
    \fBproc \fIname args body\fR
.br
    \fBpublic \fIvarName\fR ?\fIinit\fR? ?\fIconfig\fR?
.br
    \fBprotected \fIvarName\fR ?\fIinit\fR?
.br
    \fBcommon \fIvarName\fR ?\fIinit\fR?
.br
\fB}\fR
.sp
\fIclassName objName\fR ?\fIargs...\fR?
.br
\fIclassName\fR \fB#auto\fR ?\fIargs...\fR?
.br
\fIclassName\fR \fB::\fR \fIproc\fR ?\fIargs...\fR?
.sp
\fIobjName method\fR ?\fIargs...\fR?
.sp
\fICommands available within class methods/procs:\fR
.br
\fBglobal \fIvarName\fR ?\fIvarName...\fR?
.br
\fBprevious \fIcommand\fR ?\fIargs...\fR?
.br
\fBvirtual \fIcommand\fR ?\fIargs...\fR?
.BE

.SH DESCRIPTION
.PP
This command is considered obsolete, but is retained for
backward-compatibility with earlier versions of \fB[incr\ Tcl]\fR.
It has been replaced by the \fBclass\fR command, which should
be used for any new development.

.TP
\fBitcl_class \fIclassName definition\fR
Provides the definition for a class named \fIclassName\fR.  If
\fIclassName\fR is already defined, then this command returns
an error.  If the class definition is successfully parsed,
\fIclassName\fR becomes a command in the current namespace
context, handling the
creation of objects and providing access to class scope.
The class \fIdefinition\fR
is evaluated as a series of Tcl statements that define
elements within the class.  In addition to the usual
commands, the following class definition commands are recognized:
.RS
.TP
\fBinherit \fIbaseClass\fR ?\fIbaseClass\fR...?
Declares one or more base classes, causing the current class to
inherit their characteristics.  Classes must have been defined by
a previous \fBitcl_class\fR command, or must be available to the
auto-loading facility (see "AUTO-LOADING" below).  A single class
definition can contain no more than one \fBinherit\fR command.
.RS
.LP
When the same member name appears in two or more base classes,
the base class that appears first in the \fBinherit\fR list takes
precedence.  For example, if classes "Foo" and "Bar" both contain
the member "x", then the "\fBinherit\fR" statement:
.CS
inherit Foo Bar
.CE
allows "Foo::x" to be accessed simply as "x" but forces "Bar::x" (and
all other inherited members named "x") to be referenced with their
explicit "\fIclass\fR::\fImember\fR" name.
.RE
.TP
\fBconstructor \fIargs\fR ?\fIinit\fR? \fIbody\fR
Declares the argument list and body used for the constructor, which
is automatically invoked whenever an object is created.  Before
.VS
the \fIbody\fR is executed, the optional \fIinit\fR statement is
used to invoke any base class constructors that require arguments.
Variables in the \fIargs\fR specification can be accessed in the
\fIinit\fR code fragment, and passed to base class constructors.
After evaluating the \fIinit\fR statement, any base class
constructors that have not been executed are invoked without
arguments.  This ensures that all base classes are fully
constructed before the constructor \fIbody\fR is executed.
.VE
If construction is successful, the constructor always returns
the object name\-regardless of how the \fIbody\fR is defined\-and
the object name becomes a command in the current namespace context.
If construction fails, an error message is returned.
.TP
\fBdestructor \fIbody\fR
Declares the body used for the destructor, which is automatically invoked
whenever an object is deleted.  If the destructor is successful, the object
data is destroyed and the object name is removed as a command from the
interpreter.  If destruction fails, an error message is returned
and the object remains.
.RS
.LP
.VS
When an object is destroyed, all destructors in a class hierarchy
are invoked in order from most- to least-specific.  This is the
order that the classes are reported by the "\fBinfo heritage\fR"
command, and it is exactly the opposite of the default constructor
order.
.VE
.RE
.TP
\fBmethod \fIname args body\fR
Declares a method called \fIname\fR with an argument list \fIargs\fR
and a \fIbody\fR of Tcl statements.  A method is just like the usual
Tcl "proc" except that it has transparent access to
.VS
object-specific variables, as well as
.VE
common variables.  Within the class scope, a method can be invoked
like any other command\-simply by using its name.  Outside of the
class scope, the method name must be prefaced by an object
name.  Methods in a base class that are redefined in the current class
or hidden by another base class can be explicitly scoped using the
"\fIclass\fR::\fImethod\fR" syntax.
.TP
\fBproc \fIname args body\fR
Declares a proc called \fIname\fR with an argument list \fIargs\fR
and a \fIbody\fR of Tcl statements.  A proc is similar to a method,
except that it can be invoked without referring to a specific object,
and therefore has access only to common variables\-not
.VS
to object-specific variables declared with the \fBpublic\fR
and \fBprotected\fR commands.
.VE
Within the class scope, a proc can be invoked
like any other command\-simply by using its name.  In any other
namespace context, the proc is invoked using a qualified name
like "\fIclassName\fB::\fIproc\fR".
Procs in a base class that are redefined in the current
class, or hidden by another base class, can also be accessed
via their qualified name.
.TP
\fBpublic \fIvarName\fR ?\fIinit\fR? ?\fIconfig\fR?
Declares a public variable named \fIvarName\fR.  Public variables are
visible in methods within the scope of their class and any derived class.
In addition, they can be modified outside of the class scope using the special
"config" formal argument (see "ARGUMENT LISTS" above).  If the optional
\fIinit\fR is specified, it is used as the initial value of the variable
when a new object is created.  If the optional \fIconfig\fR command
is specified,
it is invoked whenever a public variable is modified via the "config"
formal argument; if the \fIconfig\fR command returns an error, the
public variable is reset to its value before configuration, and the
method handling the configuration returns an error.
.TP
\fBprotected \fIvarName\fR ?\fIinit\fR?
Declares a protected variable named \fIvarName\fR.  Protected variables
are visible in methods within the scope of their class and any derived class,
but cannot
be modified outside of the class scope.  If the optional \fIinit\fR
is specified, it is used as the initial value of the variable when a new
object is created.  Initialization forces the variable to be a simple
scalar value; uninitialized variables, on the other hand, can be used
as arrays.  All objects have a built-in protected variable named
"this" which is initialized to the instance name for the object.
.TP
\fBcommon \fIvarName\fR ?\fIinit\fR?
Declares a common variable named \fIvarName\fR.  Common variables are
shared among all objects in a class.  They are visible in methods and
procs in the scope of their class and any derived class, but cannot be
modified outside of the class scope.
If the optional \fIinit\fR is specified, it is used as the
initial value of the variable.  Initialization forces the variable to be
a simple scalar value; uninitialized variables, on the other hand, can
be used as arrays.
.RS
.LP
Once a common variable has been declared, it can be configured using
ordinary Tcl code within the class definition.  This facility is
particularly useful when the initialization of the variable is
non-trivial\-when the variable contains an array of values, for example:
.CS
itcl_class Foo {
     .
     .
    common boolean
    set boolean(true) 1
    set boolean(false) 0
}
.CE
.RE
.RE