1pluginmgr(n) Plugin management pluginmgr(n)
2______________________________________________________________________________
6
8 pluginmgr - Manage a plugin
9
11 package require Tcl 8.4
12 package require pluginmgr ?0.3?
14 ::pluginmgr objectName ?option value...?
16 ::pluginmgr::paths objectName name...
18 objectName method ?arg arg ...?
20 objectName clone
22 objectName configure
24 objectName configure option
26 objectName configure -option value...
28 objectName cget -option
30 objectName destroy
32 objectName do arg...
34 objectName interpreter
36 objectName plugin
38 objectName load string
40 objectName unload
42 objectName list
44 objectName path path
46 objectName paths
48______________________________________________________________________________
50
52 This package provides commands and objects for the generic management
53 of plugins which can be loaded into an application.
54 To avoid the implementation of yet another system to locate Tcl code
56 the system provides by this package is built on top of the regular
57 package management system. Each plugin is considered as a package and a
58 simple invokation of package require is enough to locate and load it,
59 if it exists. The only time we will need additional paths is when a
60 plugin manager is part of a wrapped application and has to be able to
61 search for plugins existing outside of that application. For this situ‐
62 ation the package provides a command to create a general set of such
63 paths based on names for the plugin manager and/or application in ques‐
64 tion.
65 The main contribution of this package is a generic framework which
67 allows the easy declaration of
68 [1] How to translate a plugin name to the name of the package imple‐
70 menting it, and vice versa.
71 [2] The list of commands a plugin has to provide as API, and also of
73 more complex checks as code.
74 [3] The list of commands expected by the plugin from the environ‐
76 ment.
77 This then allows the easy generation of plugin managers customized to
79 particular types of plugins for an application.
80 It should be noted that all plugin code is considered untrusted and
82 will always be executed within a safe interpreter. The interpreter is
83 enabled enough to allow plugins the loading of all additional packages
84 they may need.
85
87 PACKAGE COMMANDS
88 ::pluginmgr objectName ?option value...?
89 This command creates a new plugin manager object with an associ‐
90 ated Tcl command whose name is objectName. This object command
91 is explained in full detail in the sections OBJECT COMMAND and
92 OBJECT METHODS. The object command will be created under the
93 current namespace if the objectName is not fully qualified, and
94 in the specified namespace otherwise.
95 The options and their values coming after the name of the object
97 are used to set the initial configuration of the mamager object,
98 specifying the applicable plugins and their API.
99 ::pluginmgr::paths objectName name...
101 This utility command adds a set of paths to the specified
102 object, based on the given names. It will search for:
103 [1] The environment variable name_PLUGINS. Its contents will
105 be interpreted as a list of package paths. The entries
106 have to be separated by either : (unix) or ; (windows).
107 The name will be converted to upper-case letters.
109 [2] The registry entry "HKEY_LOCAL_MACHINE\SOFT‐
111 WARE\name\PLUGINS". Its contents will be interpreted as
112 a list of package paths. The entries have to be separated
113 by ;. This item is considered only when on Windows (tm).
114 The casing of letters is not changed.
116 [3] The registry entry "HKEY_CURRENT_USER\SOFTWARE\name\PLUG‐
118 INS". Its contents will be interpreted as a list of
119 package paths. The entries have to be separated by ;.
120 This item is considered only when on Windows (tm).
121 The casing of letters is not changed.
123 [4] The directory "~/.name/plugin".
125 [5] The directory "~/.name/plugins".
127 The casing of letters is not changed.
129 and add all the paths found that way to the list of package paths main‐
131 tained by the object.
132 If name is namespaced each item in the list will be repeated per prefix
134 of name, with conversion of :-sequences into the proper separator
135 (underscore for environment variables, backslash for registry entries,
136 and / for directories).
137 Examples:
139 ::pluginmgr::paths ::obj docidx
143 => env DOCIDX_PLUGINS
145 reg HKEY_LOCAL_MACHINE\SOFTWARE\docidx\PLUGINS
146 reg HKEY_CURRENT_USER\SOFTWARE\docidx\PLUGINS
147 path ~/.docidx/plugins
148 ::pluginmgr::paths ::obj doctools::idx
150 => env DOCTOOLS_PLUGINS
152 env DOCTOOLS_IDX_PLUGINS
153 reg HKEY_LOCAL_MACHINE\SOFTWARE\doctools\PLUGINS
154 reg HKEY_LOCAL_MACHINE\SOFTWARE\doctools\idx\PLUGINS
155 reg HKEY_CURRENT_USER\SOFTWARE\doctools\PLUGINS
156 reg HKEY_CURRENT_USER\SOFTWARE\doctools\idx\PLUGINS
157 path ~/.doctools/plugin
158 path ~/.doctools/idx/plugin
159 OBJECT COMMAND
162 All commands created by the command ::pluginmgr (See section PACKAGE
163 COMMANDS) have the following general form and may be used to invoke
164 various operations on their plugin manager object.
165 objectName method ?arg arg ...?
167 The method method and its arg'uments determine the exact behav‐
168 ior of the command. See section OBJECT METHODS for the detailed
169 specifications.
170 OBJECT METHODS
172 objectName clone
173 This method creates a new plugin management object and returns
174 the associated object command. The generated object is a clone
175 of the object the method was invoked on. I.e. the new object
176 will have the same configuration as the current object. With
177 regard to state, if the current object has a plugin loaded then
178 this plugin and all associated state is moved to the generated
179 clone and the current object is reset into the base state (no
180 plugin loaded). In this manner a configured plugin manager is
181 also a factory for loaded plugins.
182 objectName configure
184 The method returns a list of all known options and their current
185 values when called without any arguments.
186 objectName configure option
188 The method behaves like the method cget when called with a sin‐
189 gle argument and returns the value of the option specified by
190 said argument.
191 objectName configure -option value...
193 The method reconfigures the specified options of the object,
194 setting them to the associated values, when called with an even
195 number of arguments, at least two.
196 The legal options are described in the section OBJECT CONFIGURA‐
198 TION.
199 objectName cget -option
201 This method expects a legal configuration option as argument and
202 will return the current value of that option for the object the
203 method was invoked for.
204 The legal configuration options are described in section OBJECT
206 CONFIGURATION.
207 objectName destroy
209 This method destroys the object it is invoked for.
210 objectName do arg...
212 This method interprets its list of arguments as the words of a
213 command and invokes this command in the execution context of the
214 plugin. The result of the invoked command is made the result of
215 the method. The call will fail with an error if no valid plugin
216 has been loaded into the manager object.
217 objectName interpreter
219 This method returns the handle of the safe interpreter the cur‐
220 rent plugin is loaded into. An empty string as return value sig‐
221 nals that the manager currently has no valid plugin loaded.
222 objectName plugin
224 This method returns the name of the plugin currently loaded. An
225 empty string as return value signals that the manager currently
226 has no valid plugin loaded.
227 objectName load string
229 This method loads, validates, and initializes a named plugin
230 into the manager object.
231 The algorithm to locate and load the plugin employed is:
233 [1] If the string contains the path to an existing file then
235 this file is taken as the implementation of the plugin.
236 [2] Otherwise the plugin name is translated into a package
238 name via the value of the option -pattern and then loaded
239 through the regular package management.
240 [3] The load fails.
242 The algorithm to validate and initialize the loaded code is:
244 [1] If the option -api is non-empty introspection commands
246 are used to ascertain that the plugin provides the listed
247 commands.
248 [2] If the option -check is non-empty the specified command
250 prefix is called.
251 [3] If either of the above fails the candidate plugin is
253 unloaded again
254 [4] Otherwise all the commands specified via the option -cmds
256 are installed in the plugin.
257 A previously loaded plugin is discarded, but only if the new plugin was
259 found and sucessfully validated and initialized. Note that there will
260 be no intereference between old and new plugin as both will be put into
261 separate safe interpreters.
262 objectName unload
264 This method unloads the currently loaded plugin. It returns the
265 empty string. The call will be silently ignored if no plugin is
266 loaded at all.
267 objectName list
269 This method uses the contents of the option -pattern to find all
270 packages which can be plugins under the purview of this manager
271 object. It translates their names into plugin names and returns
272 a list containing them.
273 objectName path path
275 This methods adds the specified path to the list of additional
276 package paths to look at when searching for a plugin. It returns
277 the empty string. Duplicate paths are ignored, i.e. each path is
278 added only once. Paths are made absolute, but are not normal‐
279 ized.
280 objectName paths
282 This method returns a list containing all additional paths which
283 have been added to the plugin manager object since its creation.
284 OBJECT CONFIGURATION
286 All plugin manager objects understand the following configuration
287 options:
288 -pattern string
290 The value of this option is a glob pattern which has to contain
291 exactly one '*'-operator. All packages whose names match this
292 pattern are the plugins recognized by the manager object. And
293 vice versa, the replacement of the '*'-operator with a plugin
294 name will yield the name of the package implementing that plug‐
295 in.
296 This option has no default, except if option -name was set. It
298 has to be set before attempting to load a plugin, either
299 directly, or through option -name.
300 -api list
302 The value of this option is a list of command names, and any
303 plugin loaded has to provide these commands. Names which are not
304 fully qualified are considered to be rooted in the global names‐
305 pace. If empty no expectations are made on the plugin. The
306 default value is the empty list.
307 -check cmdprefix
309 The value of this option is interpreted as a command prefix.
310 Its purpose is to perform complex checks on a loaded plugin
311 package to validate it, which go beyond a simple list of pro‐
312 vided commands.
313 It is called with the manager object command as the only argu‐
315 ment and has to return a boolean value. A value of true will be
316 interpreted to mean that the candidate plugin passed the test.
317 The call will happen if and only if the candidate plugin already
318 passed the basic API check specified through the option -api.
319 The default value is the empty list, which causes the manager
321 object to suppress the call and to assume the candidate plugin
322 passes.
323 -cmds dict
325 The value of this option is a dictionary. It specifies the com‐
326 mands which will be made available to the plugin (as keys), and
327 the trusted commands in the environment which implement them (as
328 values). The trusted commands will be executed in the inter‐
329 preter specified by the option -cmdip. The default value is the
330 empty dictionary.
331 -cmdip ipspec
333 The value of this option is the path of the interpreter where
334 the trusted commands given to the plugin will be executed in.
335 The default is the empty string, referring to the current inter‐
336 preter.
337 -setup cmdprefix
339 The value of this option is interpreted as a command prefix.
340 It is called whenever a new safe interpreter for a plugin has
342 been created, but before a plugin is loaded. It is provided with
343 the manager object command and the interpreter handle as its
344 only arguments. Any return value will be ignored.
345 Its purpose is give a user of the plugin management the ability
347 to define commands, packages, etc. a chosen plugin may need
348 while being loaded.
349
351 This document, and the package it describes, will undoubtedly contain
352 bugs and other problems. Please report such in the category pluginmgr
353 of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
354 also report any ideas for enhancements you may have for either package
355 and/or documentation.
356 When proposing code changes, please provide unified diffs, i.e the out‐
358 put of diff -u.
359 Note further that attachments are strongly preferred over inlined
361 patches. Attachments can be made by going to the Edit form of the
362 ticket immediately after its creation, and then using the left-most
363 button in the secondary navigation bar.
364
366 plugin management, plugin search
367
369 Programming tools
370
372 Copyright (c) 2005 Andreas Kupries <andreas_kupries@users.sourceforge.net>
373tcllib 0.3 pluginmgr(n)