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diff --git a/doc/Class.3 b/doc/Class.3 new file mode 100644 index 0000000..e9bb21c --- /dev/null +++ b/doc/Class.3 @@ -0,0 +1,236 @@ +'\" +'\" 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 Tcl_Class 3 0.1 TclOO "TclOO Library Functions" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +Tcl_ClassGetMetadata, Tcl_ClassSetMetadata, Tcl_CopyObjectInstance, Tcl_GetClassAsObject, Tcl_GetObjectAsClass, Tcl_GetObjectCommand, Tcl_GetObjectNamespace, Tcl_NewObjectInstance, Tcl_ObjectDeleted, Tcl_ObjectGetMetadata, Tcl_ObjectGetMethodNameMapper, Tcl_ObjectSetMetadata, Tcl_ObjectSetMethodNameMapper \- manipulate objects and classes +.SH SYNOPSIS +.nf +\fB#include <tclOO.h>\fR +.sp +Tcl_Object +\fBTcl_GetObjectFromObj\fR(\fIinterp, objPtr\fR) +.sp +Tcl_Object +\fBTcl_GetClassAsObject\fR(\fIclass\fR) +.sp +Tcl_Class +\fBTcl_GetObjectAsClass\fR(\fIobject\fR) +.sp +Tcl_Obj * +\fBTcl_GetObjectName\fR(\fIinterp, object\fR) +.sp +Tcl_Command +\fBTcl_GetObjectCommand\fR(\fIobject\fR) +.sp +Tcl_Namespace * +\fBTcl_GetObjectNamespace\fR(\fIobject\fR) +.sp +Tcl_Object +\fBTcl_NewObjectInstance\fR(\fIinterp, class, name, nsName, objc, objv, skip\fR) +.sp +Tcl_Object +\fBTcl_CopyObjectInstance\fR(\fIinterp, object, name, nsName\fR) +.sp +int +\fBTcl_ObjectDeleted\fR(\fIobject\fR) +.sp +ClientData +\fBTcl_ObjectGetMetadata\fR(\fIobject, metaTypePtr\fR) +.sp +\fBTcl_ObjectSetMetadata\fR(\fIobject, metaTypePtr, metadata\fR) +.sp +ClientData +\fBTcl_ClassGetMetadata\fR(\fIclass, metaTypePtr\fR) +.sp +\fBTcl_ClassSetMetadata\fR(\fIclass, metaTypePtr, metadata\fR) +.sp +Tcl_ObjectMapMethodNameProc +\fBTcl_ObjectGetMethodNameMapper\fR(\fIobject\fR) +.sp +\fBTcl_ObjectSetMethodNameMapper\fR(\fIobject\fR, \fImethodNameMapper\fR) +.SH ARGUMENTS +.AS ClientData metadata in/out +.AP Tcl_Interp *interp in/out +Interpreter providing the context for looking up or creating an object, and +into whose result error messages will be written on failure. +.AP Tcl_Obj *objPtr in +The name of the object to look up. +.AP Tcl_Object object in +Reference to the object to operate upon. +.AP Tcl_Class class in +Reference to the class to operate upon. +.AP "const char" *name in +The name of the object to create, or NULL if a new unused name is to be +automatically selected. +.AP "const char" *nsName in +The name of the namespace to create for the object's private use, or NULL if a +new unused name is to be automatically selected. +.AP int objc in +The number of elements in the \fIobjv\fR array. +.AP "Tcl_Obj *const" *objv in +The arguments to the command to create the instance of the class. +.AP int skip in +The number of arguments at the start of the argument array, \fIobjv\fR, that +are not arguments to any constructors. +.AP Tcl_ObjectMetadataType *metaTypePtr in +The type of \fImetadata\fR being set with \fBTcl_ClassSetMetadata\fR or +retrieved with \fBTcl_ClassGetMetadata\fR. +.AP ClientData metadata in +An item of metadata to attach to the class, or NULL to remove the metadata +associated with a particular \fImetaTypePtr\fR. +.AP "Tcl_ObjectMapMethodNameProc" "methodNameMapper" in +A pointer to a function to call to adjust the mapping of objects and method +names to implementations, or NULL when no such mapping is required. +.BE +.SH DESCRIPTION +.PP +Objects are typed entities that have a set of operations ("methods") +associated with them. Classes are objects that can manufacture objects. Each +class can be viewed as an object itself; the object view can be retrieved +using \fBTcl_GetClassAsObject\fR which always returns the object when applied +to a non-destroyed class, and an object can be viewed as a class with the aid +of the \fBTcl_GetObjectAsClass\fR (which either returns the class, or NULL if +the object is not a class). An object may be looked up using the +\fBTcl_GetObjectFromObj\fR function, which either returns an object or NULL +(with an error message in the interpreter result) if the object cannot be +found. The correct way to look up a class by name is to look up the object +with that name, and then to use \fBTcl_GetObjectAsClass\fR. +.PP +Every object has its own command and namespace associated with it. The command +may be retrieved using the \fBTcl_GetObjectCommand\fR function, the name of +the object (and hence the name of the command) with \fBTcl_GetObjectName\fR, +and the namespace may be retrieved using the \fBTcl_GetObjectNamespace\fR +function. Note that the Tcl_Obj reference returned by \fBTcl_GetObjectName\fR +is a shared reference. +.PP +Instances of classes are created using \fBTcl_NewObjectInstance\fR, which +takes creates an object from any class (and which is internally called by both +the \fBcreate\fR and \fBnew\fR methods of the \fBoo::class\fR class). It takes +parameters that optionally give the name of the object and namespace to +create, and which describe the arguments to pass to the class's constructor +(if any). The result of the function will be either a reference to the newly +created object, or NULL if the creation failed (when an error message will be +left in the interpreter result). In addition, objects may be copied by using +\fBTcl_CopyObjectInstance\fR which creates a copy of an object without running +any constructors. +.SH "OBJECT AND CLASS METADATA" +.PP +Every object and every class may have arbitrary amounts of metadata attached +to it, which the object or class attaches no meaning to beyond what is +described in a Tcl_ObjectMetadataType structure instance. Metadata to be +attached is described by the the type of the metadata (given in the +\fImetaTypePtr\fR argument) and an arbitrary pointer (the \fImetadata\fR +argument) that are given to \fBTcl_ObjectSetMetadata\fR and +\fBTcl_ClassSetMetadata\fR, and a particular piece of metadata can be +retrieved given its type using \fBTcl_ObjectGetMetadata\fR and +\fBTcl_ClassGetMetadata\fR. If the \fImetadata\fR parameter to either +\fBTcl_ObjectSetMetadata\fR or \fBTcl_ClassSetMetadata\fR is NULL, the +metadata is removed if it was attached, and the results of +\fBTcl_ObjectGetMetadata\fR and \fBTcl_ClassGetMetadata\fR are NULL if the +given type of metadata was not attached. It is not an error to request or +remove a piece of metadata that was not attached. +.SS "TCL_OBJECTMETADATATYPE STRUCTURE" +.PP +The contents of the Tcl_ObjectMetadataType structure are as follows: +.PP +.CS +typedef const struct { + int \fIversion\fR; + const char *\fIname\fR; + Tcl_ObjectMetadataDeleteProc *\fIdeleteProc\fR; + Tcl_CloneProc *\fIcloneProc\fR; +} \fBTcl_ObjectMetadataType\fR; +.CE +.PP +The \fIversion\fR field allows for future expansion of the structure, and +should always be declared equal to TCL_OO_METADATA_VERSION_CURRENT. The +\fIname\fR field provides a human-readable name for the type, and is reserved +for debugging. +.PP +The \fIdeleteProc\fR field gives a function of type +Tcl_ObjectMetadataDeleteProc that is used to delete a particular piece of +metadata, and is called when the attached metadata is replaced or removed; the +field must not be NULL. +.PP +The \fIcloneProc\fR field gives a function that is used to copy a piece of +metadata (used when a copy of an object is created using +\fBTcl_CopyObjectInstance\fR); if NULL, the metadata will be just directly +copied. +.SS "TCL_OBJECTMETADATADELETEPROC FUNCTION SIGNATURE" +.PP +Functions matching this signature are used to delete metadata associated with +a class or object. +.PP +.CS +typedef void \fBTcl_ObjectMetadataDeleteProc\fR( + ClientData \fImetadata\fR); +.CE +.PP +The \fImetadata\fR argument gives the address of the metadata to be +deleted. +.SS "TCL_CLONEPROC FUNCTION SIGNATURE" +.PP +Functions matching this signature are used to create copies of metadata +associated with a class or object. +.PP +.CS +typedef int \fBTcl_CloneProc\fR( + Tcl_Interp *\fIinterp\fR, + ClientData \fIsrcMetadata\fR, + ClientData *\fIdstMetadataPtr\fR); +.CE +.PP +The \fIinterp\fR argument gives a place to write an error message when the +attempt to clone the object is to fail, in which case the clone procedure must +also return TCL_ERROR; it should return TCL_OK otherwise. +The \fIsrcMetadata\fR argument gives the address of the metadata to be cloned, +and the cloned metadata should be written into the variable pointed to by +\fIdstMetadataPtr\fR; a NULL should be written if the metadata is to not be +cloned but the overall object copy operation is still to succeed. +.SH "OBJECT METHOD NAME MAPPING" +It is possible to control, on a per-object basis, what methods are invoked +when a particular method is invoked. Normally this is done by looking up the +method name in the object and then in the class hierarchy, but fine control of +exactly what the value used to perform the look up is afforded through the +ability to set a method name mapper callback via +\fBTcl_ObjectSetMethodNameMapper\fR (and its introspection counterpart, +\fBTcl_ObjectGetMethodNameMapper\fR, which returns the current mapper). The +current mapper (if any) is invoked immediately before looking up what chain of +method implementations is to be used. +.SS "TCL_OBJECTMAPMETHODNAMEPROC FUNCTION SIGNATURE" +The \fITcl_ObjectMapMethodNameProc\fR callback is defined as follows: +.PP +.CS +typedef int \fBTcl_ObjectMapMethodNameProc\fR( + Tcl_Interp *\fIinterp\fR, + Tcl_Object \fIobject\fR, + Tcl_Class *\fIstartClsPtr\fR, + Tcl_Obj *\fImethodNameObj\fR); +.CE +.PP +If the result is TCL_OK, the remapping is assumed to have been done. If the +result is TCL_ERROR, an error message will have been left in \fIinterp\fR and +the method call will fail. If the result is TCL_BREAK, the standard method +name lookup rules will be used; the behavior of other result codes is +currently undefined. The \fIobject\fR parameter says which object is being +processed. The \fIstartClsPtr\fR parameter points to a variable that contains +the first class to provide a definition in the method chain to process, or +NULL if the whole chain is to be processed (the argument itself is never +NULL); this variable may be updated by the callback. The \fImethodNameObj\fR +parameter gives an unshared object containing the name of the method being +invoked, as provided by the user; this object may be updated by the callback. +.SH "SEE ALSO" +Method(3), oo::class(n), oo::copy(n), oo::define(n), oo::object(n) +.SH KEYWORDS +class, constructor, object +.\" Local variables: +.\" mode: nroff +.\" fill-column: 78 +.\" End: |