1Tcl_Class(3) TclOO Library Functions Tcl_Class(3)
2______________________________________________________________________________
6
8 Tcl_ClassGetMetadata, Tcl_ClassSetMetadata, Tcl_CopyObjectInstance,
9 Tcl_GetClassAsObject, Tcl_GetObjectAsClass, Tcl_GetObjectCommand,
10 Tcl_GetObjectFromObj, Tcl_GetObjectName, Tcl_GetObjectNamespace,
11 Tcl_NewObjectInstance, Tcl_ObjectDeleted, Tcl_ObjectGetMetadata,
12 Tcl_ObjectGetMethodNameMapper, Tcl_ObjectSetMetadata, Tcl_ObjectSet‐
13 MethodNameMapper - manipulate objects and classes
14
16 #include <tclOO.h>
17 Tcl_Object
19 Tcl_GetObjectFromObj(interp, objPtr)
20 Tcl_Object
22 Tcl_GetClassAsObject(class)
23 Tcl_Class
25 Tcl_GetObjectAsClass(object)
26 Tcl_Obj *
28 Tcl_GetObjectName(interp, object)
29 Tcl_Command
31 Tcl_GetObjectCommand(object)
32 Tcl_Namespace *
34 Tcl_GetObjectNamespace(object)
35 Tcl_Object
37 Tcl_NewObjectInstance(interp, class, name, nsName, objc, objv, skip)
38 Tcl_Object
40 Tcl_CopyObjectInstance(interp, object, name, nsName)
41 int
43 Tcl_ObjectDeleted(object)
44 ClientData
46 Tcl_ObjectGetMetadata(object, metaTypePtr)
47 Tcl_ObjectSetMetadata(object, metaTypePtr, metadata)
49 ClientData
51 Tcl_ClassGetMetadata(class, metaTypePtr)
52 Tcl_ClassSetMetadata(class, metaTypePtr, metadata)
54 Tcl_ObjectMapMethodNameProc
56 Tcl_ObjectGetMethodNameMapper(object)
57 Tcl_ObjectSetMethodNameMapper(object, methodNameMapper)
59
61 Tcl_Interp *interp (in/out) Interpreter providing the context for
62 looking up or creating an object, and
63 into whose result error messages will
64 be written on failure.
65 Tcl_Obj *objPtr (in) The name of the object to look up.
67 Tcl_Object object (in) Reference to the object to operate
69 upon.
70 Tcl_Class class (in) Reference to the class to operate
72 upon.
73 const char *name (in) The name of the object to create, or
75 NULL if a new unused name is to be
76 automatically selected.
77 const char *nsName (in) The name of the namespace to create
79 for the object's private use, or NULL
80 if a new unused name is to be auto‐
81 matically selected. The namespace
82 must not already exist.
83 int objc (in) The number of elements in the objv
85 array.
86 Tcl_Obj *const *objv (in) The arguments to the command to cre‐
88 ate the instance of the class.
89 int skip (in) The number of arguments at the start
91 of the argument array, objv, that are
92 not arguments to any constructors.
93 Tcl_ObjectMetadataType *metaTypePtr (in)
95 The type of metadata being set with
96 Tcl_ClassSetMetadata or retrieved
97 with Tcl_ClassGetMetadata.
98 ClientData metadata (in) An item of metadata to attach to the
100 class, or NULL to remove the metadata
101 associated with a particular
102 metaTypePtr.
103 Tcl_ObjectMapMethodNameProc methodNameMapper (in)
105 A pointer to a function to call to
106 adjust the mapping of objects and
107 method names to implementations, or
108 NULL when no such mapping is
109 required.
110______________________________________________________________________________
111
113 Objects are typed entities that have a set of operations ("methods")
114 associated with them. Classes are objects that can manufacture objects.
115 Each class can be viewed as an object itself; the object view can be
116 retrieved using Tcl_GetClassAsObject which always returns the object
117 when applied to a non-destroyed class, and an object can be viewed as a
118 class with the aid of the Tcl_GetObjectAsClass (which either returns
119 the class, or NULL if the object is not a class). An object may be
120 looked up using the Tcl_GetObjectFromObj function, which either returns
121 an object or NULL (with an error message in the interpreter result) if
122 the object cannot be found. The correct way to look up a class by name
123 is to look up the object with that name, and then to use Tcl_GetObjec‐
124 tAsClass.
125 Every object has its own command and namespace associated with it. The
127 command may be retrieved using the Tcl_GetObjectCommand function, the
128 name of the object (and hence the name of the command) with Tcl_GetOb‐
129 jectName, and the namespace may be retrieved using the Tcl_GetObject‐
130 Namespace function. Note that the Tcl_Obj reference returned by
131 Tcl_GetObjectName is a shared reference.
132 Instances of classes are created using Tcl_NewObjectInstance, which
134 creates an object from any class (and which is internally called by
135 both the create and new methods of the oo::class class). It takes
136 parameters that optionally give the name of the object and namespace to
137 create, and which describe the arguments to pass to the class's con‐
138 structor (if any). The result of the function will be either a refer‐
139 ence to the newly created object, or NULL if the creation failed (when
140 an error message will be left in the interpreter result). In addition,
141 objects may be copied by using Tcl_CopyObjectInstance which creates a
142 copy of an object without running any constructors.
143
145 Every object and every class may have arbitrary amounts of metadata
146 attached to it, which the object or class attaches no meaning to beyond
147 what is described in a Tcl_ObjectMetadataType structure instance. Meta‐
148 data to be attached is described by the type of the metadata (given in
149 the metaTypePtr argument) and an arbitrary pointer (the metadata argu‐
150 ment) that are given to Tcl_ObjectSetMetadata and Tcl_ClassSetMetadata,
151 and a particular piece of metadata can be retrieved given its type
152 using Tcl_ObjectGetMetadata and Tcl_ClassGetMetadata. If the metadata
153 parameter to either Tcl_ObjectSetMetadata or Tcl_ClassSetMetadata is
154 NULL, the metadata is removed if it was attached, and the results of
155 Tcl_ObjectGetMetadata and Tcl_ClassGetMetadata are NULL if the given
156 type of metadata was not attached. It is not an error to request or
157 remove a piece of metadata that was not attached.
158 TCL_OBJECTMETADATATYPE STRUCTURE
160 The contents of the Tcl_ObjectMetadataType structure are as follows:
161 typedef const struct {
163 int version;
164 const char *name;
165 Tcl_ObjectMetadataDeleteProc *deleteProc;
166 Tcl_CloneProc *cloneProc;
167 } Tcl_ObjectMetadataType;
168 The version field allows for future expansion of the structure, and
170 should always be declared equal to TCL_OO_METADATA_VERSION_CURRENT. The
171 name field provides a human-readable name for the type, and is reserved
172 for debugging.
173 The deleteProc field gives a function of type Tcl_ObjectMeta‐
175 dataDeleteProc that is used to delete a particular piece of metadata,
176 and is called when the attached metadata is replaced or removed; the
177 field must not be NULL.
178 The cloneProc field gives a function that is used to copy a piece of
180 metadata (used when a copy of an object is created using Tcl_CopyOb‐
181 jectInstance); if NULL, the metadata will be just directly copied.
182 TCL_OBJECTMETADATADELETEPROC FUNCTION SIGNATURE
184 Functions matching this signature are used to delete metadata associ‐
185 ated with a class or object.
186 typedef void Tcl_ObjectMetadataDeleteProc(
188 ClientData metadata);
189 The metadata argument gives the address of the metadata to be deleted.
191 TCL_CLONEPROC FUNCTION SIGNATURE
193 Functions matching this signature are used to create copies of metadata
194 associated with a class or object.
195 typedef int Tcl_CloneProc(
197 Tcl_Interp *interp,
198 ClientData srcMetadata,
199 ClientData *dstMetadataPtr);
200 The interp argument gives a place to write an error message when the
202 attempt to clone the object is to fail, in which case the clone proce‐
203 dure must also return TCL_ERROR; it should return TCL_OK otherwise.
204 The srcMetadata argument gives the address of the metadata to be
205 cloned, and the cloned metadata should be written into the variable
206 pointed to by dstMetadataPtr; a NULL should be written if the metadata
207 is to not be cloned but the overall object copy operation is still to
208 succeed.
209
211 It is possible to control, on a per-object basis, what methods are
212 invoked when a particular method is invoked. Normally this is done by
213 looking up the method name in the object and then in the class hierar‐
214 chy, but fine control of exactly what the value used to perform the
215 look up is afforded through the ability to set a method name mapper
216 callback via Tcl_ObjectSetMethodNameMapper (and its introspection coun‐
217 terpart, Tcl_ObjectGetMethodNameMapper, which returns the current map‐
218 per). The current mapper (if any) is invoked immediately before looking
219 up what chain of method implementations is to be used.
220 TCL_OBJECTMAPMETHODNAMEPROC FUNCTION SIGNATURE
222 The Tcl_ObjectMapMethodNameProc callback is defined as follows:
223 typedef int Tcl_ObjectMapMethodNameProc(
225 Tcl_Interp *interp,
226 Tcl_Object object,
227 Tcl_Class *startClsPtr,
228 Tcl_Obj *methodNameObj);
229 If the result is TCL_OK, the remapping is assumed to have been done. If
231 the result is TCL_ERROR, an error message will have been left in interp
232 and the method call will fail. If the result is TCL_BREAK, the standard
233 method name lookup rules will be used; the behavior of other result
234 codes is currently undefined. The object parameter says which object is
235 being processed. The startClsPtr parameter points to a variable that
236 contains the first class to provide a definition in the method chain to
237 process, or NULL if the whole chain is to be processed (the argument
238 itself is never NULL); this variable may be updated by the callback.
239 The methodNameObj parameter gives an unshared object containing the
240 name of the method being invoked, as provided by the user; this object
241 may be updated by the callback.
242
244 Method(3), oo::class(n), oo::copy(n), oo::define(n), oo::object(n)
245
247 class, constructor, object
248TclOO 0.1 Tcl_Class(3)