1self(n) TclOO Commands self(n)
2______________________________________________________________________________
6
8 self - method call internal introspection
9
11 package require TclOO
12 self ?subcommand?
14______________________________________________________________________________
15
17 The self command, which should only be used from within the context of
18 a call to a method (i.e. inside a method, constructor or destructor
19 body) is used to allow the method to discover information about how it
20 was called. It takes an argument, subcommand, that tells it what sort
21 of information is actually desired; if omitted the result will be the
22 same as if self object was invoked. The supported subcommands are:
23 self call
25 This returns a two-element list describing the method implemen‐
26 tations used to implement the current call chain. The first ele‐
27 ment is the same as would be reported by info object call for
28 the current method (except that this also reports useful values
29 from within constructors and destructors, whose names are
30 reported as <constructor> and <destructor> respectively), and
31 the second element is an index into the first element's list
32 that indicates which actual implementation is currently execut‐
33 ing (the first implementation to execute is always at index 0).
34 self caller
36 When the method was invoked from inside another object method,
37 this subcommand returns a three element list describing the con‐
38 taining object and method. The first element describes the
39 declaring object or class of the method, the second element is
40 the name of the object on which the containing method was
41 invoked, and the third element is the name of the method (with
42 the strings <constructor> and <destructor> indicating construc‐
43 tors and destructors respectively).
44 self class
46 This returns the name of the class that the current method was
47 defined within. Note that this will change as the chain of
48 method implementations is traversed with next, and that if the
49 method was defined on an object then this will fail.
50 If you want the class of the current object, you need to use
52 this other construct:
53 info object class [self object]
55 self filter
57 When invoked inside a filter, this subcommand returns a three
58 element list describing the filter. The first element gives the
59 name of the object or class that declared the filter (note that
60 this may be different from the object or class that provided the
61 implementation of the filter), the second element is either
62 object or class depending on whether the declaring entity was an
63 object or class, and the third element is the name of the fil‐
64 ter.
65 self method
67 This returns the name of the current method (with the strings
68 <constructor> and <destructor> indicating constructors and
69 destructors respectively).
70 self namespace
72 This returns the name of the unique namespace of the object that
73 the method was invoked upon.
74 self next
76 When invoked from a method that is not at the end of a call
77 chain (i.e. where the next command will invoke an actual method
78 implementation), this subcommand returns a two element list
79 describing the next element in the method call chain; the first
80 element is the name of the class or object that declares the
81 next part of the call chain, and the second element is the name
82 of the method (with the strings <constructor> and <destructor>
83 indicating constructors and destructors respectively). If
84 invoked from a method that is at the end of a call chain, this
85 subcommand returns the empty string.
86 self object
88 This returns the name of the object that the method was invoked
89 upon.
90 self target
92 When invoked inside a filter implementation, this subcommand
93 returns a two element list describing the method being filtered.
94 The first element will be the name of the declarer of the
95 method, and the second element will be the actual name of the
96 method.
97
99 This example shows basic use of self to provide information about the
100 current object:
101 oo::class create c {
103 method foo {} {
104 puts "this is the [self] object"
105 }
106 }
107 c create a
108 c create b
109 a foo → prints "this is the ::a object"
110 b foo → prints "this is the ::b object"
111 This demonstrates what a method call chain looks like, and how travers‐
113 ing along it changes the index into it:
114 oo::class create c {
116 method x {} {
117 puts "Cls: [self call]"
118 }
119 }
120 c create a
121 oo::objdefine a {
122 method x {} {
123 puts "Obj: [self call]"
124 next
125 puts "Obj: [self call]"
126 }
127 }
128 a x → Obj: {{method x object method} {method x ::c method}} 0
129 → Cls: {{method x object method} {method x ::c method}} 1
130 → Obj: {{method x object method} {method x ::c method}} 0
131
133 info(n), next(n)
134
136 call, introspection, object
137TclOO 0.1 self(n)