1delegation(n) [incr Tcl] delegation(n)
2______________________________________________________________________________
6
8 itcl::delegation - delegate methods, procs or options to other objects
9 Parts of this description are "borrowed" from Tcl extension [snit], as
11 the functionality is mostly identical.
12
14 This is new functionality in [incr Tcl] where the API can still
15 change!!
16
18 delegate method methodName to componentName ?as targetName?
19 delegate method methodName ?to componentName? using pattern
20 delegate method * ?to componentName? ?using pattern? ?except methodName methodName ...?
21 delegate proc procName to componentName ?as targetName?
23 delegate proc procName ?to componentName? using pattern
24 delegate proc * ?to componentName? ?using pattern? ?except procName procName ...?
25 delegate option optionSpec to componentName
27 delegate option optionSpec to componentName as targetname?
28 delegate option * to componentName
29 delegate option * to componentName except optionName optionname ...
30______________________________________________________________________________
31
34 The delegate command is used inside an [incr Tcl] extendedclass/wid‐
35 get/widgetadaptor definition to delegate methods/procs/options to other
36 objects for handling.
37 delegate method methodName to componentName ?as targetName?
39 This form of delegate method delegates method methodName to com‐
40 ponent componentName. That is, when method methdoNameame is
41 called on an instance of this type, the method and its arguments
42 will be passed to the named component's command instead. That
43 is, the following statement
44 delegate method wag to tail
46 is roughly equivalent to this explicitly defined method:
48 method wag {args} {
50 uplevel $tail wag $args
51 }
52 The optional as clause allows you to specify the delegated
54 method name and possibly add some arguments:
55 delegate method wagtail to tail as "wag briskly"
57 A method cannot be both locally defined and delegated.
59 delegate method methodName ?to componentName? using pattern
61 In this form of the delegate statement, the using clause is used
62 to specify the precise form of the command to which method name
63 name is delegated. The to clause is optional, since the chosen
64 command might not involve any particular component.
65 The value of the using clause is a list that may contain any or
67 all of the following substitution codes; these codes are substi‐
68 tuted with the described value to build the delegated command
69 prefix. Note that the following two statements are equivalent:
70 delegate method wag to tail
72 delegate method wag to tail using "%c %m"
73 Each element of the list becomes a single element of the dele‐
75 gated command --it is never reparsed as a string.
76 Substitutions:
78 %% This is replaced with a single "%". Thus, to pass the
80 string "%c" to the command as an argument, you'd write
81 "%%c".
82 %c This is replaced with the named component's command.
84 %j This is replaced by the method name; if the name consists
86 of multiple tokens, they are joined by underscores ("_").
87 %m This is replaced with the final token of the method name;
89 if the method name has one token, this is identical to
90 %M.
91 %M This is replaced by the method name; if the name consists
93 of multiple tokens, they are joined by space characters.
94 %n This is replaced with the name of the instance's private
96 namespace.
97 %s This is replaced with the name of the instance command.
99 %t This is replaced with the fully qualified type name.
101 %w This is replaced with the original name of the instance
103 command; for Itcl widgets and widget adaptors, it will be
104 the Tk window name. It remains constant, even if the
105 instance command is renamed.
106 delegate method * ?to componentName? ?using pattern? ?except methodName
108 methodName ...?
109 In this form all unknown method names are delegeted to the spec‐
110 ified component. The except clause can be used to specify a list
111 of exceptions, i.e., method names that will not be so delegated.
112 The using clause is defined as given above. In this form, the
113 statement must contain the to clause, the using clause, or both.
114 In fact, the "*" can be a list of two or more tokens whose last
116 element is "*", as in the following example:
117 delegate method {tail *} to tail
119 This implicitly defines the method tail whose subcommands will
121 be delegated to the tail component.
122 The definitions for delegate proc ... are the same as for
124 method, the only difference being, that this is for procs.
125 delegate option namespec to comp
127 delegate option namespec to comp as target
129 delegate option * to comp
131 delegate option * to comp except exceptions
133 Defines a delegated option; the namespec is defined as for the
134 option statement. When the configure, configurelist, or cget
135 instance method is used to set or retrieve the option's value,
136 the equivalent configure or cget command will be applied to the
137 component as though the option was defined with the following
138 -configuremethod and -cgetmethod:
139 method ConfigureMethod {option value} {
141 $comp configure $option $value
142 }
143 method CgetMethod {option} {
145 return [$comp cget $option]
146 }
147 Note that delegated options never appear in the itcl_options
149 array. If the as clause is specified, then the target option
150 name is used in place of name.
151 delegate option * ?except optionName optionName ...?
153 This form delegates all unknown options to the specified compo‐
154 nent. The except clause can be used to specify a list of excep‐
155 tions, i.e., option names that will not be so delegated.
156 Warning: options can only be delegated to a component if it sup‐
158 ports the configure and cget instance methods.
159 An option cannot be both locally defined and delegated. TBD:
161 Continue from here.
162
164 delegation, option, method, proc
165itcl 4.0 delegation(n)