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diff --git a/doc/define.n b/doc/define.n new file mode 100644 index 0000000..6bdd9c5 --- /dev/null +++ b/doc/define.n @@ -0,0 +1,404 @@ +'\" +'\" 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. +'\" +.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 ?\fI\-slotOperation\fR? ?\fImethodName ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) +.VE +sets or updates the list of method names that are used to guard whether +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. +.VS +By default, this slot works by appending. +.VE +.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. The \fIcmdName\fR will always be resolved using the +rules of the invoking objects' namespaces, i.e., when \fIcmdName\fR is not +fully-qualified, the command will be searched for in each object's namespace, +using the instances' namespace's path, or by looking in the global namespace. +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 or updates a method that is implemented as a procedure-like +script. 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 ?\fI\-slotOperation\fR? ?\fIclassName ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) +.VE +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. +.VS +By default, this slot works by replacement. +.VE +.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 ?\fI\-slotOperation\fR? \fR?\fIclassName ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) +.VE +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, that an empty parent class is equivalent to +\fBoo::object\fR, and that the parent classes of \fBoo::object\fR and +\fBoo::class\fR may not be modified. +.VS +By default, this slot works by replacement. +.VE +.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. +.TP +\fBvariable\fR ?\fI\-slotOperation\fR? ?\fIname ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) arranges for each of the named +variables to be automatically made +available in the methods, constructor and destructor declared by the class +being defined. Each variable name must not have any namespace +separators and must not look like an array access. All variables will be +actually present in the instance object on which the method is executed. Note +that the variable lists declared by a superclass or subclass are completely +disjoint, as are variable lists declared by instances; the list of variable +names is just for methods (and constructors and destructors) declared by this +class. By default, this slot works by appending. +.VE +.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 ?\fI\-slotOperation\fR? ?\fImethodName ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) +.VE +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. Note +that the actual list of filters also depends on the filters set upon any +classes that the object is an instance of. +.VS +By default, this slot works by appending. +.VE +.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 ?\fI\-slotOperation\fR? ?\fIclassName ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) +.VE +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. +.VS +By default, this slot works by replacement. +.VE +.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. +.TP +\fBvariable\fR ?\fI\-slotOperation\fR? ?\fIname ...\fR? +.VS +This slot (see \fBSLOTTED DEFINITIONS\fR below) arranges for each of the named +variables to be automatically made available in the methods declared by the +object being defined. Each variable name must not have any namespace +separators and must not look like an array access. All variables will be +actually present in the object on which the method is executed. Note that the +variable lists declared by the classes and mixins of which the object is an +instance are completely disjoint; the list of variable names is just for +methods declared by this object. By default, this slot works by appending. +.SH "SLOTTED DEFINITIONS" +Some of the configurable definitions of a class or object are \fIslotted +definitions\fR. This means that the configuration is implemented by a slot +object, that is an instance of the class \fBoo::Slot\fR, which manages a list +of values (class names, variable names, etc.) that comprises the contents of +the slot. The class defines three operations (as methods) that may be done on +the slot: +.VE +.TP +\fIslot\fR \fB\-append\fR ?\fImember ...\fR? +.VS +This appends the given \fImember\fR elements to the slot definition. +.VE +.TP +\fIslot\fR \fB\-clear\fR +.VS +This sets the slot definition to the empty list. +.VE +.TP +\fIslot\fR \fB\-set\fR ?\fImember ...\fR? +.VS +This replaces the slot definition with the given \fImember\fR elements. +.PP +A consequence of this is that any use of a slot's default operation where the +first member argument begins with a hyphen will be an error. One of the above +operations should be used explicitly in those circumstances. +.SS "SLOT IMPLEMENTATION" +Internally, slot objects also define a method \fB\-\-default\-operation\fR +which is forwarded to the default operation of the slot (thus, for the class +.QW \fBvariable\fR +slot, this is forwarded to +.QW "\fBmy \-append\fR" ), +and these methods which provide the implementation interface: +.VE +.TP +\fIslot\fR \fBGet\fR +.VS +Returns a list that is the current contents of the slot. This method must +always be called from a stack frame created by a call to \fBoo::define\fR or +\fBoo::objdefine\fR. +.VE +.TP +\fIslot\fR \fBSet \fIelementList\fR +.VS +Sets the contents of the slot to the list \fIelementList\fR and returns the +empty string. This method must always be called from a stack frame created by +a call to \fBoo::define\fR or \fBoo::objdefine\fR. +.PP +The implementation of these methods is slot-dependent (and responsible for +accessing the correct part of the class or object definition). Slots also have +an unknown method handler to tie all these pieces together, and they hide +their \fBdestroy\fR method so that it is not invoked inadvertently. It is +\fIrecommended\fR that any user changes to the slot mechanism be restricted to +defining new operations whose names start with a hyphen. +.VE +.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 +.PP +This example shows how additional classes can be mixed into an object. It also +shows how \fBmixin\fR is a slot that supports appending: +.PP +.CS +oo::object create inst +inst m1 \fI\(-> error "unknown method m1"\fR +inst m2 \fI\(-> error "unknown method m2"\fR + +oo::class create A { + \fBmethod\fR m1 {} { + puts "red brick" + } +} +\fBoo::objdefine\fR inst { + \fBmixin\fR A +} +inst m1 \fI\(-> prints "red brick"\fR +inst m2 \fI\(-> error "unknown method m2"\fR + +oo::class create B { + \fBmethod\fR m2 {} { + puts "blue brick" + } +} +\fBoo::objdefine\fR inst { + \fBmixin -append\fR B +} +inst m1 \fI\(-> prints "red brick"\fR +inst m2 \fI\(-> prints "blue brick"\fR +.CE +.SH "SEE ALSO" +next(n), oo::class(n), oo::object(n) +.SH KEYWORDS +class, definition, method, object, slot +.\" Local variables: +.\" mode: nroff +.\" fill-column: 78 +.\" End: |