| '\" |
| '\" 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: itcl_class.n,v 1.1 1998/07/27 18:42:01 stanton 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 |
| '\" to .AP later. If args are omitted, default tab stops are used. |
| '\" |
| '\" .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 |
| .nf |
| .ti 0 |
| .mk ^t |
| \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 |
| .\} |
| .bp |
| 'fi |
| .ev |
| .if \\n(^b \{\ |
| .mk ^y |
| .nr ^b 2 |
| .\} |
| .if \\n(^v \{\ |
| .mk ^Y |
| .\} |
| .. |
| '\" # 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 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 |
| |
| .SH CLASS USAGE |
| .PP |
| When a class definition has been loaded (or made available to the |
| auto-loader), the class name can be used as a command. |
| .TP |
| \fIclassName objName\fR ?\fIargs...\fR? |
| Creates a new object in class \fIclassName\fR with the name \fIobjName\fR. |
| Remaining arguments are passed to the constructor. If construction is |
| successful, the object name is returned and this name becomes a command |
| in the current namespace context. Otherwise, an error is returned. |
| .TP |
| \fIclassName\fR #auto ?\fIargs...\fR? |
| Creates a new object in class \fIclassName\fR with an automatically |
| generated name. Names are of the form \fIclassName<number>\fR, |
| .VS |
| where the \fIclassName\fR part is modified to start with a lowercase |
| letter. In class "Toaster", for example, the "\fB#auto\fR" specification |
| would produce names toaster0, toaster1, etc. Remaining arguments are |
| .VE |
| passed to the constructor. If construction is successful, the object |
| name is returned and this name becomes a command in the current |
| namespace context. Otherwise, an error is returned. |
| .TP |
| \fIclassName\fR :: \fIproc\fR ?\fIargs...\fR? |
| Used outside of the class scope to invoke a class proc named \fIproc\fR. |
| Class procs are like ordinary Tcl procs, except that they are executed |
| in the scope of the class and therefore have transparent |
| access to common data members. |
| .RS |
| .LP |
| .VS |
| Notice that, unlike any other scope qualifier in \fB[incr\ Tcl]\fR, the "::" |
| shown above is surrounded by spaces. This is unnecessary with the |
| new namespace facility, and is considered obsolete. The capability |
| is still supported, however, to provide backward-compatibility with |
| earlier versions. |
| .VE |
| .RE |
| |
| .SH OBJECT USAGE |
| .TP |
| \fIobjName method\fR ?\fIargs...\fR? |
| Invokes a method named \fImethod\fR to operate on the specified object. |
| Remaining arguments are passed to the method. The method name can |
| be "constructor", "destructor", any method name appearing in the |
| class definition, or any of the following built-in methods. |
| .SH BUILT-IN METHODS |
| .TP |
| \fIobjName\fR \fBisa \fIclassName\fR |
| Returns non-zero if the given \fIclassName\fR can be found in the |
| object's heritage, and zero otherwise. |
| .TP |
| \fIobjName\fR \fBdelete\fR |
| Invokes the destructor associated with an object. |
| If the destructor is successful, data associated with the object is |
| deleted and \fIobjName\fR is removed as a command from the |
| interpreter. Returns the empty string, regardless of the destructor |
| body. |
| .RS |
| .LP |
| .VS |
| The built-in \fBdelete\fR method has been replaced by the |
| "\fBdelete object\fR" command in the global namespace, and |
| is considered obsolete. The capability is still supported, |
| however, to provide backward-compatibility with earlier versions. |
| .VE |
| .RE |
| .TP |
| \fIobjName\fR \fBinfo \fIoption\fR ?\fIargs...\fR? |
| Returns information related to the class definition or to |
| a particular object named \fIobjName\fR. |
| The \fIoption\fR parameter includes the following things, as well as |
| the options recognized by the usual Tcl "info" command: |
| .RS |
| .TP |
| \fIobjName\fR \fBinfo class\fR |
| .VS |
| Returns the name of the most-specific class for object \fIobjName\fR. |
| .VE |
| .TP |
| \fIobjName\fR \fBinfo inherit\fR |
| Returns the list of base classes as they were defined in the |
| "\fBinherit\fR" command, or an empty string if this class |
| has no base classes. |
| .TP |
| \fIobjName\fR \fBinfo heritage\fR |
| Returns the current class name and the entire list of base classes in |
| the order that they are traversed for member lookup and object |
| destruction. |
| .TP |
| \fIobjName\fR \fBinfo method\fR ?\fImethodName\fR? ?\fB-args\fR? ?\fB-body\fR? |
| With no arguments, this command returns a list of all class methods. |
| If \fImethodName\fR is specified, it returns information for a specific method. |
| If neither of the optional \fB-args\fR or \fB-body\fR flags is specified, |
| a complete method definition is returned as a list of three elements |
| including the method name, argument list and body. Otherwise, the |
| requested information is returned without the method name. |
| If the \fImethodName\fR is not recognized, an empty string is returned. |
| .TP |
| \fIobjName\fR \fBinfo proc\fR ?\fIprocName\fR? ?\fB-args\fR? ?\fB-body\fR? |
| With no arguments, this command returns a list of all class procs. |
| If \fIprocName\fR is specified, it returns information for a specific proc. |
| If neither of the optional \fB-args\fR or \fB-body\fR flags is specified, |
| a complete proc definition is returned as a list of three elements |
| including the proc name, argument list and body. Otherwise, the |
| requested information is returned without the proc name. |
| If the \fIprocName\fR is not recognized, an empty string is returned. |
| .TP |
| \fIobjName\fR \fBinfo public\fR ?\fIvarName\fR? ?\fB-init\fR? ?\fB-value\fR? ?\fB-config\fR? |
| With no arguments, this command returns a list of all public variables. |
| If \fIvarName\fR is specified, it returns information for a specific public |
| variable. |
| If none of the optional \fB-init\fR, \fB-value\fR or \fB-config\fR flags |
| are specified, all available information is returned as a list of four |
| elements including the variable name, initial value, current value, |
| and configuration commands. Otherwise, the requested information is |
| returned without the variable name. |
| If the \fIvarName\fR is not recognized, an empty string is returned. |
| .TP |
| \fIobjName\fR \fBinfo protected\fR ?\fIvarName\fR? ?\fB-init\fR? ?\fB-value\fR? |
| With no arguments, this command returns a list of all protected variables. |
| If \fIvarName\fR is specified, it returns information for a specific protected |
| variable. |
| If neither of the optional \fB-init\fR or \fB-value\fR flags is specified, |
| all available information is returned as a list of three elements |
| including the variable name, initial value and current value. |
| Otherwise, the requested information is returned without the variable name. |
| If the \fIvarName\fR is not recognized, an empty string is returned. |
| .TP |
| \fIobjName\fR \fBinfo common\fR ?\fIvarName\fR? ?\fB-init\fR? ?\fB-value\fR? |
| With no arguments, this command returns a list of all common variables. |
| If \fIvarName\fR is specified, it returns information for a specific common |
| variable. |
| If neither of the optional \fB-init\fR or \fB-value\fR flags is specified, |
| all available information is returned as a list of three elements |
| including the variable name, initial value and current value. |
| Otherwise, the requested information is returned without the variable name. |
| If the \fIvarName\fR is not recognized, an empty string is returned. |
| .RE |
| .SH OTHER BUILT-IN COMMANDS |
| The following commands are also available within the scope of each class. |
| They cannot be accessed from outside of the class as proper methods or |
| procs; rather, they are useful inside the class when implementing its |
| functionality. |
| .TP |
| \fBglobal \fIvarName\fR ?\fIvarName...\fR? |
| Creates a link to one or more global variables in the current |
| namespace context. Global variables can also be accessed in |
| other namespaces by including namespace qualifiers in \fIvarName\fR. |
| This is useful when communicating with Tk widgets that rely on global |
| variables. |
| .TP |
| \fBprevious \fIcommand\fR ?\fIargs...\fR? |
| Invokes \fIcommand\fR in the scope of the most immediate base class |
| .VS |
| (i.e., the "previous" class) for the object. For classes using single |
| .VE |
| inheritance, this facility can be used to avoid hard-wired base class |
| references of the form "\fIclass\fR::\fIcommand\fR", making code easier |
| to maintain. For classes using multiple inheritance, the utility of |
| this function is dubious. |
| If the class at the relevant scope has no base class, an error is returned. |
| .TP |
| \fBvirtual \fIcommand\fR ?\fIargs...\fR? |
| .VS |
| Invokes \fIcommand\fR in the scope of the most-specific class for the |
| object. The methods within a class are automatically virtual; whenever |
| an unqualified method name is used, it always refers to the most-specific |
| implementation for that method. This function provides a way of |
| evaluating code fragments in a base class that have access to the |
| most-specific object information. It is useful, for example, for |
| creating base classes that can capture and save an object's state. |
| It inverts the usual notions of object-oriented programming, however, |
| and should therefore be used sparingly. |
| .VE |
| |
| .SH AUTO-LOADING |
| .PP |
| Class definitions need not be loaded explicitly; they can be loaded as |
| needed by the usual Tcl auto-loading facility. Each directory containing |
| class definition files should have an accompanying "tclIndex" file. |
| Each line in this file identifies a Tcl procedure or \fB[incr\ Tcl]\fR |
| class definition and the file where the definition can be found. |
| .PP |
| For example, suppose a directory contains the definitions for classes |
| "Toaster" and "SmartToaster". Then the "tclIndex" file for this |
| directory would look like: |
| .CS |
| # Tcl autoload index file, version 2.0 for [incr Tcl] |
| # This file is generated by the "auto_mkindex" command |
| # and sourced to set up indexing information for one or |
| # more commands. Typically each line is a command that |
| # sets an element in the auto_index array, where the |
| # element name is the name of a command and the value is |
| # a script that loads the command. |
| |
| set auto_index(::Toaster) "source $dir/Toaster.itcl" |
| set auto_index(::SmartToaster) "source $dir/SmartToaster.itcl" |
| .PP |
| The \fBauto_mkindex\fR command is used to automatically |
| generate "tclIndex" files. |
| .CE |
| The auto-loader must be made aware of this directory by appending |
| the directory name to the "auto_path" variable. When this is in |
| place, classes will be auto-loaded as needed when used in an |
| application. |
| |
| .SH KEYWORDS |
| class, object, object-oriented |