[comment {-*- tcl -*- paths manpage}] [manpage_begin pluginmgr n 0.3] [copyright {2005 Andreas Kupries }] [moddesc {Plugin management}] [titledesc {Manage a plugin}] [category {Programming tools}] [require Tcl 8.4] [require pluginmgr [opt 0.3]] [description] [keywords {plugin management} {plugin search}] This package provides commands and objects for the generic management of plugins which can be loaded into an application. [para] To avoid the implementation of yet another system to locate Tcl code the system provides by this package is built on top of the regular package management system. Each plugin is considered as a package and a simple invokation of [cmd {package require}] is enough to locate and load it, if it exists. The only time we will need additional paths is when a plugin manager is part of a wrapped application and has to be able to search for plugins existing outside of that application. For this situation the package provides a command to create a general set of such paths based on names for the plugin manager and/or application in question. [para] The main contribution of this package is a generic framework which allows the easy declaration of [list_begin enumerated] [enum] How to translate a plugin name to the name of the package implementing it, and vice versa. [enum] The list of commands a plugin has to provide as API, and also of more complex checks as code. [enum] The list of commands expected by the plugin from the environment. [list_end] This then allows the easy generation of plugin managers customized to particular types of plugins for an application. [para] It should be noted that all plugin code is considered untrusted and will always be executed within a safe interpreter. The interpreter is enabled enough to allow plugins the loading of all additional packages they may need. [section {PUBLIC API}] [subsection {PACKAGE COMMANDS}] [list_begin definitions] [call [cmd ::pluginmgr] [arg objectName] [opt [arg "option value"]...]] This command creates a new plugin manager object with an associated Tcl command whose name is [arg objectName]. This [term object] command is explained in full detail in the sections [sectref {OBJECT COMMAND}] and [sectref {OBJECT METHODS}]. The object command will be created under the current namespace if the [arg objectName] is not fully qualified, and in the specified namespace otherwise. [para] The options and their values coming after the name of the object are used to set the initial configuration of the mamager object, specifying the applicable plugins and their API. [call [cmd ::pluginmgr::paths] [arg objectName] [arg name]...] This utility command adds a set of paths to the specified object, based on the given [arg name]s. It will search for: [list_begin enumerated] [enum] The environment variable [var [arg name]_PLUGINS]. Its contents will be interpreted as a list of package paths. The entries have to be separated by either [const :] (unix) or [const \;] (windows). [para] The name will be converted to upper-case letters. [enum] The registry entry "HKEY_LOCAL_MACHINE\SOFTWARE\[arg name]\PLUGINS". Its contents will be interpreted as a list of package paths. The entries have to be separated by [const \;]. This item is considered only when on Windows (tm). [para] The casing of letters is not changed. [enum] The registry entry "HKEY_CURRENT_USER\SOFTWARE\[arg name]\PLUGINS". Its contents will be interpreted as a list of package paths. The entries have to be separated by [const \;]. This item is considered only when on Windows (tm). [para] The casing of letters is not changed. [enum] The directory [file "~/.[arg name]/plugin"]. [enum] The directory [file "~/.[arg name]/plugins"]. [para] The casing of letters is not changed. [list_end] [para] and add all the paths found that way to the list of package paths maintained by the object. [para] If [arg name] is namespaced each item in the list will be repeated per prefix of [arg name], with conversion of :-sequences into the proper separator (underscore for environment variables, backslash for registry entries, and / for directories). [para] Examples: [para] [example { ::pluginmgr::paths ::obj docidx => env DOCIDX_PLUGINS reg HKEY_LOCAL_MACHINE\SOFTWARE\docidx\PLUGINS reg HKEY_CURRENT_USER\SOFTWARE\docidx\PLUGINS path ~/.docidx/plugins ::pluginmgr::paths ::obj doctools::idx => env DOCTOOLS_PLUGINS env DOCTOOLS_IDX_PLUGINS reg HKEY_LOCAL_MACHINE\SOFTWARE\doctools\PLUGINS reg HKEY_LOCAL_MACHINE\SOFTWARE\doctools\idx\PLUGINS reg HKEY_CURRENT_USER\SOFTWARE\doctools\PLUGINS reg HKEY_CURRENT_USER\SOFTWARE\doctools\idx\PLUGINS path ~/.doctools/plugin path ~/.doctools/idx/plugin }] [list_end] [subsection {OBJECT COMMAND}] All commands created by the command [cmd ::pluginmgr] (See section [sectref {PACKAGE COMMANDS}]) have the following general form and may be used to invoke various operations on their plugin manager object. [list_begin definitions] [call [cmd objectName] [method method] [opt [arg "arg arg ..."]]] The method [method method] and its [arg arg]'uments determine the exact behavior of the command. See section [sectref {OBJECT METHODS}] for the detailed specifications. [list_end] [subsection {OBJECT METHODS}] [list_begin definitions] [call [arg objectName] [method clone]] This method creates a new plugin management object and returns the associated object command. The generated object is a clone of the object the method was invoked on. I.e. the new object will have the same configuration as the current object. With regard to state, if the current object has a plugin loaded then this plugin and all associated state is moved to the generated clone and the current object is reset into the base state (no plugin loaded). In this manner a configured plugin manager is also a factory for loaded plugins. [call [arg objectName] [method configure]] The method returns a list of all known options and their current values when called without any arguments. [call [arg objectName] [method configure] [arg option]] The method behaves like the method [method cget] when called with a single argument and returns the value of the option specified by said argument. [call [arg objectName] [method configure] [option -option] [arg value]...] The method reconfigures the specified [option option]s of the object, setting them to the associated [arg value]s, when called with an even number of arguments, at least two. [para] The legal options are described in the section [sectref {OBJECT CONFIGURATION}]. [call [arg objectName] [method cget] [option -option]] This method expects a legal configuration option as argument and will return the current value of that option for the object the method was invoked for. [para] The legal configuration options are described in section [sectref {OBJECT CONFIGURATION}]. [call [arg objectName] [method destroy]] This method destroys the object it is invoked for. [call [arg objectName] [method do] [arg arg]...] This method interprets its list of arguments as the words of a command and invokes this command in the execution context of the plugin. The result of the invoked command is made the result of the method. The call will fail with an error if no valid plugin has been loaded into the manager object. [call [arg objectName] [method interpreter]] This method returns the handle of the safe interpreter the current plugin is loaded into. An empty string as return value signals that the manager currently has no valid plugin loaded. [call [arg objectName] [method plugin]] This method returns the name of the plugin currently loaded. An empty string as return value signals that the manager currently has no valid plugin loaded. [call [arg objectName] [method load] [arg string]] This method loads, validates, and initializes a named plugin into the manager object. [para] The algorithm to locate and load the plugin employed is: [list_begin enumerated] [enum] If the [arg string] contains the path to an existing file then this file is taken as the implementation of the plugin. [enum] Otherwise the plugin name is translated into a package name via the value of the option [option -pattern] and then loaded through the regular package management. [enum] The load fails. [list_end] [para] The algorithm to validate and initialize the loaded code is: [list_begin enumerated] [enum] If the option [option -api] is non-empty introspection commands are used to ascertain that the plugin provides the listed commands. [enum] If the option [option -check] is non-empty the specified command prefix is called. [enum] If either of the above fails the candidate plugin is unloaded again [enum] Otherwise all the commands specified via the option [option -cmds] are installed in the plugin. [list_end] [para] A previously loaded plugin is discarded, but only if the new plugin was found and sucessfully validated and initialized. Note that there will be no intereference between old and new plugin as both will be put into separate safe interpreters. [call [arg objectName] [method unload]] This method unloads the currently loaded plugin. It returns the empty string. The call will be silently ignored if no plugin is loaded at all. [call [arg objectName] [method list]] This method uses the contents of the option [option -pattern] to find all packages which can be plugins under the purview of this manager object. It translates their names into plugin names and returns a list containing them. [call [arg objectName] [method path] [arg path]] This methods adds the specified [arg path] to the list of additional package paths to look at when searching for a plugin. It returns the empty string. Duplicate paths are ignored, i.e. each path is added only once. Paths are made absolute, but are not normalized. [call [arg objectName] [method paths]] This method returns a list containing all additional paths which have been added to the plugin manager object since its creation. [list_end] [subsection {OBJECT CONFIGURATION}] All plugin manager objects understand the following configuration options: [list_begin options] [opt_def -pattern [arg string]] The value of this option is a glob pattern which has to contain exactly one '*'-operator. All packages whose names match this pattern are the plugins recognized by the manager object. And vice versa, the replacement of the '*'-operator with a plugin name will yield the name of the package implementing that plugin. [para] This option has no default, except if option [option -name] was set. It has to be set before attempting to load a plugin, either directly, or through option [option -name]. [opt_def -api [arg list]] The value of this option is a list of command names, and any plugin loaded has to provide these commands. Names which are not fully qualified are considered to be rooted in the global namespace. If empty no expectations are made on the plugin. The default value is the empty list. [opt_def -check [arg cmdprefix]] The value of this option is interpreted as a command prefix. Its purpose is to perform complex checks on a loaded plugin package to validate it, which go beyond a simple list of provided commands. [para] It is called with the manager object command as the only argument and has to return a boolean value. A value of [const true] will be interpreted to mean that the candidate plugin passed the test. The call will happen if and only if the candidate plugin already passed the basic API check specified through the option [option -api]. [para] The default value is the empty list, which causes the manager object to suppress the call and to assume the candidate plugin passes. [opt_def -cmds [arg dict]] The value of this option is a dictionary. It specifies the commands which will be made available to the plugin (as keys), and the trusted commands in the environment which implement them (as values). The trusted commands will be executed in the interpreter specified by the option [option -cmdip]. The default value is the empty dictionary. [opt_def -cmdip [arg ipspec]] The value of this option is the path of the interpreter where the trusted commands given to the plugin will be executed in. The default is the empty string, referring to the current interpreter. [opt_def -setup [arg cmdprefix]] The value of this option is interpreted as a command prefix. [para] It is called whenever a new safe interpreter for a plugin has been created, but before a plugin is loaded. It is provided with the manager object command and the interpreter handle as its only arguments. Any return value will be ignored. [para] Its purpose is give a user of the plugin management the ability to define commands, packages, etc. a chosen plugin may need while being loaded. [list_end] [section {BUGS, IDEAS, FEEDBACK}] This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category [emph pluginmgr] of the [uri {http://sourceforge.net/tracker/?group_id=12883} {Tcllib SF Trackers}]. Please also report any ideas for enhancements you may have for either package and/or documentation. [manpage_end]