Implementation of TIP #257. Incomplete due to missing Win build support.

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+'\"
+'\" Copyright (c) 2007 Donal K. Fellows
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\"
+'\" RCS: @(#) $Id: define.n,v 1.1 2008/05/31 11:42:12 dkf Exp $
+'\"
+.so man.macros
+.TH define n 0.3 TclOO "TclOO Commands"
+.BS
+'\" Note:  do not modify the .SH NAME line immediately below!
+.SH NAME
+oo::define, oo::objdefine \- define and configure classes and objects
+.SH SYNOPSIS
+.nf
+package require TclOO
+
+\fBoo::define\fI class defScript\fR
+\fBoo::define\fI class subcommand arg\fR ?\fIarg ...\fR?
+\fBoo::objdefine\fI object defScript\fR
+\fBoo::objdefine\fI object subcommand arg\fR ?\fIarg ...\fR?
+.fi
+.BE
+
+.SH DESCRIPTION
+The \fBoo::define\fR command is used to control the configuration of classes,
+and the \fBoo::objdefine\fR command is used to control the configuration of
+objects (including classes as instance objects), with the configuration being
+applied to the entity named in the \fIclass\fR or the \fIobject\fR argument.
+Configuring a class also updates the
+configuration of all subclasses of the class and all objects that are
+instances of that class or which mix it in (as modified by any per-instance
+configuration). The way in which the configuration is done is controlled by
+either the \fIdefScript\fR argument or by the \fIsubcommand\fR and following
+\fIarg\fR arguments; when the second is present, it is exactly as if all the
+arguments from \fIsubcommand\fR onwards are made into a list and that list is
+used as the \fIdefScript\fR argument.
+.SS "CONFIGURING CLASSES"
+.PP
+The following commands are supported in the \fIdefScript\fR for
+\fBoo::define\fR, each of which may also be used in the \fIsubcommand\fR form:
+.TP
+\fBconstructor\fI argList bodyScript\fR
+.
+This creates or updates the constructor for a class. The formal arguments to
+the constructor (defined using the same format as for the Tcl \fBproc\fR
+command) will be \fIargList\fR, and the body of the constructor will be
+\fIbodyScript\fR. When the body of the constructor is evaluated, the current
+namespace of the constructor will be a namespace that is unique to the object
+being constructed. Within the constructor, the \fBnext\fR command should be
+used to call the superclasses' constructors. If \fIbodyScript\fR is the empty
+string, the constructor will be deleted.
+.TP
+\fBdeletemethod\fI name\fR ?\fIname ...\fR
+.
+This deletes each of the methods called \fIname\fR from a class. The methods
+must have previously existed in that class. Does not affect the superclasses
+of the class, nor does it affect the subclasses or instances of the class
+(except when they have a call chain through the class being modified).
+.TP
+\fBdestructor\fI bodyScript\fR
+.
+This creates or updates the destructor for a class. Destructors take no
+arguments, and the body of the destructor will be \fIbodyScript\fR. The
+destructor is called when objects of the class are deleted, and when called
+will have the object's unique namespace as the current namespace. Destructors
+should use the \fBnext\fR command to call the superclasses' destructors. Note
+that destructors are not called in all situations (e.g. if the interpreter is
+destroyed). If \fIbodyScript\fR is the empty string, the destructor will be
+deleted.
+.RS
+Note that errors during the evaluation of a destructor \fIare not returned\fR
+to the code that causes the destruction of an object. Instead, they are passed
+to the currently-defined \fBbgerror\fR handler.
+.RE
+.TP
+\fBexport\fI name \fR?\fIname ...\fR?
+.
+This arranges for each of the named methods, \fIname\fR, to be exported
+(i.e. usable outside an instance through the instance object's command) by the
+class being defined. Note that the methods themselves may be actually defined
+by a superclass; subclass exports override superclass visibility, and may in
+turn be overridden by instances.
+.TP
+\fBfilter\fR ?\fImethodName ...\fR?
+.
+This sets or updates the list of method names that are used to guard whether a
+method call to instances of the class may be called and what the method's
+results are. Each \fImethodName\fR names a single filtering method (which may
+be exposed or not exposed); it is not an error for a non-existent method to be
+named since they may be defined by subclasses. If no \fImethodName\fR
+arguments are present, the list of filter names is set to empty.
+.TP
+\fBforward\fI name cmdName \fR?\fIarg ...\fR?
+.
+This creates or updates a forwarded method called \fIname\fR. The method
+is defined be forwarded to the command called \fIcmdName\fR, with additional
+arguments, \fIarg\fR etc., added before those arguments specified by the
+caller of the method. Forwarded methods should be deleted using the
+\fBmethod\fR subcommand. The method will be exported if \fIname\fR starts with
+a lower-case letter, and non-exported otherwise.
+.TP
+\fBmethod\fI name argList bodyScript\fR
+.
+This creates, updates or deletes a method. The name of the method is
+\fIname\fR, the formal arguments to the method (defined using the same format
+as for the Tcl \fBproc\fR command) will be \fIargList\fR, and the body of the
+method will be \fIbodyScript\fR. When the body of the method is evaluated, the
+current namespace of the method will be a namespace that is unique to the
+current object. The method will be exported if \fIname\fR starts with a
+lower-case letter, and non-exported otherwise; this behavior can be overridden
+via \fBexport\fR and \fBunexport\fR.
+.TP
+\fBmixin\fR ?\fIclassName ...\fR?
+.
+This sets or updates the list of additional classes that are to be mixed into
+all the instances of the class being defined. Each \fIclassName\fR argument
+names a single class that is to be mixed in; if no classes are present, the
+list of mixed-in classes is set to be empty.
+.TP
+\fBrenamemethod\fI fromName toName\fR
+.
+This renames the method called \fIfromName\fR in a class to \fItoName\fR. The
+method must have previously existed in the class, and \fItoName\fR must not
+previously refer to a method in that class. Does not affect the superclasses
+of the class, nor does it affect the subclasses or instances of the class
+(except when they have a call chain through the class being modified). Does
+not change the export status of the method; if it was exported before, it will
+be afterwards.
+.TP
+\fBself\fI subcommand arg ...\fR
+.TP
+\fBself\fI script\fR
+.
+This command is equivalent to calling \fBoo::objdefine\fR on the class being
+defined (see \fBCONFIGURING OBJECTS\fR below for a description of the
+supported values of \fIsubcommand\fR). It follows the same general pattern of
+argument handling as the \fBoo::define\fR and \fBoo::objdefine\fR commands,
+and
+.QW "\fBoo::define \fIcls \fBself \fIsubcommand ...\fR"
+operates identically to
+.QW "\fBoo::objdefine \fIcls subcommand ...\fR" .
+.TP
+\fBsuperclass\fI className \fR?\fIclassName ...\fR?
+.
+This allows the alteration of the superclasses of the class being defined.
+Each \fIclassName\fR argument names one class that is to be a superclass of
+the defined class. Note that objects must not be changed from being classes to
+being non-classes or vice-versa.
+.TP
+\fBunexport\fI name \fR?\fIname ...\fR?
+.
+This arranges for each of the named methods, \fIname\fR, to be not exported
+(i.e. not usable outside the instance through the instance object's command,
+but instead just through the \fBmy\fR command visible in each object's
+context) by the class being defined. Note that the methods themselves may be
+actually defined by a superclass; subclass unexports override superclass
+visibility, and may be overridden by instance unexports.
+.SS "CONFIGURING OBJECTS"
+.PP
+The following commands are supported in the \fIdefScript\fR for
+\fBoo::objdefine\fR, each of which may also be used in the \fIsubcommand\fR
+form:
+.TP
+\fBclass\fI className\fR
+.
+This allows the class of an object to be changed after creation. Note that the
+class's constructors are not called when this is done, and so the object may
+well be in an inconsistent state unless additional configuration work is done.
+.TP
+\fBdeletemethod\fI name\fR ?\fIname ...\fR
+.
+This deletes each of the methods called \fIname\fR from an object. The methods
+must have previously existed in that object. Does not affect the classes that
+the object is an instance of.
+.TP
+\fBexport\fI name \fR?\fIname ...\fR?
+.
+This arranges for each of the named methods, \fIname\fR, to be exported
+(i.e. usable outside the object through the object's command) by the object
+being defined. Note that the methods themselves may be actually defined by a
+class or superclass; object exports override class visibility.
+.TP
+\fBfilter\fR ?\fImethodName ...\fR?
+.
+This sets or updates the list of method names that are used to guard whether a
+method call to the object may be called and what the method's results are.
+Each \fImethodName\fR names a single filtering method (which may be exposed or
+not exposed); it is not an error for a non-existent method to be named. If no
+\fImethodName\fR arguments are present, the list of filter names is set to
+empty. Note that the actual list of filters also depends on the filters set
+upon any classes that the object is an instance of.
+.TP
+\fBforward\fI name cmdName \fR?\fIarg ...\fR?
+.
+This creates or updates a forwarded object method called \fIname\fR. The
+method is defined be forwarded to the command called \fIcmdName\fR, with
+additional arguments, \fIarg\fR etc., added before those arguments specified
+by the caller of the method. Forwarded methods should be deleted using the
+\fBmethod\fR subcommand. The method will be exported if \fIname\fR starts with
+a lower-case letter, and non-exported otherwise.
+.TP
+\fBmethod\fI name argList bodyScript\fR
+.
+This creates, updates or deletes an object method. The name of the method is
+\fIname\fR, the formal arguments to the method (defined using the same format
+as for the Tcl \fBproc\fR command) will be \fIargList\fR, and the body of the
+method will be \fIbodyScript\fR. When the body of the method is evaluated, the
+current namespace of the method will be a namespace that is unique to the
+object. The method will be exported if \fIname\fR starts with a lower-case
+letter, and non-exported otherwise.
+.TP
+\fBmixin\fR ?\fIclassName ...\fR?
+.
+This sets or updates a per-object list of additional classes that are to be
+mixed into the object. Each argument, \fIclassName\fR, names a single class
+that is to be mixed in; if no classes are present, the list of mixed-in
+classes is set to be empty.
+.TP
+\fBrenamemethod\fI fromName toName\fR
+.
+This renames the method called \fIfromName\fR in an object to \fItoName\fR.
+The method must have previously existed in the object, and \fItoName\fR must
+not previously refer to a method in that object. Does not affect the classes
+that the object is an instance of. Does not change the export status of the
+method; if it was exported before, it will be afterwards.
+.TP
+\fBunexport\fI name \fR?\fIname ...\fR?
+.
+This arranges for each of the named methods, \fIname\fR, to be not exported
+(i.e. not usable outside the object through the object's command, but instead
+just through the \fBmy\fR command visible in the object's context) by the
+object being defined. Note that the methods themselves may be actually defined
+by a class; instance unexports override class visibility.
+.SH EXAMPLES
+This example demonstrates how to use both forms of the \fBoo::define\fR and
+\fBoo::objdefine\fR commands (they work in the same way), as well as
+illustrating four of the subcommands of them.
+.PP
+.CS
+oo::class create c
+c create o
+\fBoo::define\fR c \fBmethod\fR foo {} {
+    puts "world"
+}
+\fBoo::objdefine\fR o {
+    \fBmethod\fR bar {} {
+        my Foo "hello "
+        my foo
+    }
+    \fBforward\fR Foo ::puts -nonewline
+    \fBunexport\fR foo
+}
+o bar                \fI\(-> prints "hello world"\fR
+o foo                \fI\(-> error "unknown method foo"\fR
+o Foo Bar            \fI\(-> error "unknown method Foo"\fR
+\fBoo::objdefine\fR o \fBrenamemethod\fR bar lollipop
+o lollipop           \fI\(-> prints "hello world"\fR
+.CE
+.SH "SEE ALSO"
+next(n), oo::class(n), oo::object(n)
+.SH KEYWORDS
+class, definition, method, object
+
+.\" Local variables:
+.\" mode: nroff
+.\" fill-column: 78
+.\" End: