Files
qt-creator/doc/api/plugin-metadata.qdoc
hjk 99bcc00199 ExtensionSystem: Remove PluginManager::getObjectByClassName
Not used anymore inside Qt Creator.

If 3rd party code really relies on this function, it can use the
function locally, or, likely switch to the still supported
getObjectByName or getObject.

Change-Id: I041877b3e0630e6b257055dec5e10baf68c83546
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
2018-04-11 06:47:18 +00:00

344 lines
14 KiB
Plaintext

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Creator documentation.
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** GNU Free Documentation License Usage
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** Documentation License version 1.3 as published by the Free Software
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/*!
\page plugin-meta-data.html
\title Plugin Meta Data
The meta data file of a plugin is a JSON file that contains all
information that is necessary for loading the plugin's library,
determining whether plugins are to be loaded and in which order (depending
on e.g. dependencies). In addition, it contains textual descriptions of
who created the plugin, what it is for, and where to find more information about it.
The file must be located in one of the include search paths when compiling the plugin,
and must have the \c .json extension. The JSON file is compiled into the plugin as meta data,
which then is read by \QC when loading plugins.
\section2 Main Keys
The main keys that are used to identify your your plugin and define default loading behavior,
consist of the mandatory keys \c Name and \c Version, and the optional keys \c CompatVersion,
\c Experimental, \c DisabledByDefault, \c Required and \c Platform.
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Name
\li String
\li This is used as an identifier for the plugin and can e.g.
be referenced in other plugin's dependencies.
\row
\li Version
\li String
\li Version string in the form \c{x.y.z_n}, used for identifying
the plugin. Also see \l{A Note on Plugin Versions}.
\row
\li CompatVersion
\li String
\li Optional. If not given, it is implicitly
set to the same value as \c Version. The compatibility version
states which version of this plugin the current version is
binary backward compatible with and is used to resolve dependencies
on this plugin. I.e. a \c Version of \c{2.1.1} and a
\c CompatVersion of \c{2.0.0} means that this version \c{2.1.1} of the plugin
is binary backward compatible with all versions of the plugin down to \c{2.0.0}
(inclusive).
\row
\li Experimental
\li Boolean
\li Optional. Defaults to \c false.
Experimental plugins are not loaded by default but must be explicitly
enabled by the user. This attribute should be enabled for new plugins which have the
potential to negatively affect the user experience.
\row
\li DisabledByDefault
\li Boolean
\li Optional. Defaults to \c false.
If set, the respective plugin is not loaded by default but must be explicitly
enabled by the user. This should be done for plugins which are not expected
to be used by so many people as to justify the additional resource consumption.
\row
\li HiddenByDefault
\li Boolean
\li Optional. Defaults to \c false.
If set, the plugin is not shown in the default view in the
\uicontrol {About Plugins...} dialog, but only if the user requests seeing all
plugins. It is still shown with the \c{-version} command line option.
\row
\li Required
\li Boolean
\li Optional. Defaults to \c false.
Is used as a hint for the \uicontrol{About Plugins...} dialog, that the user may not
manually disable this plugin. Only used for the Core plugin.
\row
\li Platform
\li String
\li Optional. A regular expression that matches the names of the platforms the plugin
works on. Omitting the tag implies that the plugin is loaded on all platforms.
\endtable
\section2 Plugin-describing Keys
These are solely used for more detailed (user centric) description of the plugin. All of these
are optional.
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Category
\li String
\li Defaults to \c Utilities. Is used to put related plugins
under the same tree node in the plugin overview \uicontrol{About Plugins...}.
\row
\li Vendor
\li String
\li String that describes the plugin creator/vendor,
like \c{MyCompany}.
\row
\li Copyright
\li String
\li A short copyright notice, like \c{(C) 2016 MyCompany}.
\row
\li License
\li String or array of strings
\li Possibly multi-line license information about the plugin.
Should still be kept relatively short, since the UI is not
designed for long texts.
\row
\li Description
\li String or array of strings
\li Possibly multi-line description of what the plugin is supposed
to provide.
Should still be kept relatively short, since the UI is not
designed for long texts.
\row
\li Url
\li String
\li Link to further information about the plugin, like
\c{http://www.mycompany-online.com/products/greatplugin}.
\endtable
\section2 Dependencies
A plugin can have dependencies on other plugins. These are
specified in the plugin meta data, to ensure that
these other plugins are loaded before this plugin.
Dependencies are declared with the key \c Dependency, which contains an array of JSON objects
with required keys \c Name and \c Version, and optional key \c Type.
The following formulas illustrate how the dependency information is matched.
In the formulas the name of the required plugin (as defined in the \c Name of the dependency
object) is denoted as \c DependencyName
and the required version of the plugin is denoted as \c DependencyVersion.
A plugin with given \c Name, \c Version and \c CompatVersion
as defined in the plugin meta data matches
the dependency if
\list
\li its \c Name matches \c DependencyName, and
\li \c {CompatVersion <= DependencyVersion <= Version}.
\endlist
For example a dependency
\code
{
"Name" : "SomeOtherPlugin",
"Version" : "2.3.0_2"
}
\endcode
would be matched by a plugin with
\code
{
"Name" : "SomeOtherPlugin",
"Version" : "3.1.0",
"CompatVersion" : "2.2.0",
...
}
\endcode
since the name matches, and the version \c{2.3.0_2} given in the dependency tag
lies in the range of \c{2.2.0} and \c{3.1.0}.
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Dependencies
\li Array of dependency objects
\li Describes the dependencies on other plugins.
\endtable
A dependency object is a JSON object with the following keys:
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Name
\li String
\li The name of the plugin, on which this plugin relies.
\row
\li Version
\li String
\li The version to which the plugin must be compatible to
fill the dependency, in the form \c{x.y.z_n}.
Can be empty if the version does not matter.
\row
\li Type
\li String
\li Optional. Value \c Required, \c Optional, or \c Test. Defines if the dependency is
a hard requirement, optional, or required for running the plugin's tests.
Defaults to \c{Required}.
\endtable
\section3 Optional Dependencies
A plugin can specify that a dependency on another plugin is optional, by adding
\c {"Type" : "Optional"} to the dependency object:
\list
\li If the dependency can be resolved, the plugin and
its dependency are loaded and initialized as for \c Required dependencies.
\li If the dependency cannot be resolved, the plugin is loaded and initialized
as if the dependency was not declared at all.
\endlist
The plugin is not informed about the existence of optional dependencies in any way. Since the
dependency might be loaded or not, the plugin may also not link against the dependency.
A common way to access objects from optional dependencies is to get the object from the
\l{The Plugin Manager, the Object Pool, and Registered Objects}{global object pool}
via ExtensionSystem::PluginManager::getObjectByName() and use QMetaObject functions to call
functions on it.
\section3 Test Dependencies
When the user runs the application with the \c{-test} command line argument, only
the specified plugins and their dependencies are loaded. This is done in order to
speed up the execution of tests by avoiding the loading of unneeded plugins.
A plugin can specify additional dependencies that are required for running its
tests, but not for its normal execution, by declaring dependencies with
\c {"Type" : "Test"}. Test dependencies are force loaded, and do not affect load order.
This type of dependency is not transitive.
\section2 Command Line Arguments
Plugins can register command line arguments that the user can give
when starting the application. These command line arguments are shown
with a one-line description when the user runs the application with
the \c{-help} command line argument, and the plugin manager does its command
line parsing and sanity checks based on that information.
If the plugin manager finds matching command line arguments for a plugin,
it passes them on to the plugin's
\l{ExtensionSystem::IPlugin::initialize()}{initialize()} function.
Command line arguments are defined through the key \c Arguments, which contains an array
of argument objects. Each individual argument object has the required key \c Name, and
optional keys \c Parameter and \c Description.
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Arguments
\li Array of argument objects
\li Describes the command line arguments that the plugin wants to handle.
\endtable
An argument object is a JSON object with the following keys:
\table
\header
\li Key
\li Value Type
\li Meaning
\row
\li Name
\li String
\li The command line argument itself, including the \c - prefix, e.g.
\c{-my-parameter}.
\row
\li Parameter
\li String
\li Optional. If this is given, the command line argument expects an
additional parameter, e.g. \c{-my-parameter somevalue}. The
value of this attribute is used as a very short description of the
parameter for the user.
\row
\li Description
\li String
\li Optional. A (one-line) description of the argument for the command line argument help.
\endtable
\section2 Example \c Test.json
\code
{
"Name" : "Test",
"Version" : "1.0.1",
"CompatVersion" : "1.0.0",
"Vendor" : "My Company",
"Copyright" : "(C) 2016 MyCompany",
"License" : [
"This is a default license bla",
"blubbblubb",
"end of terms"
],
"Category" : "My Company Additions",
"Description" : [
"This plugin is just a test.",
"It demonstrates the great use of the plugin meta data."
],
"Url" : "http://www.mycompany-online.com/products/greatplugin",
"Arguments" : [
{
"Name" : "-variant",
"Parameter" : "fancy|boring",
"Description" : "Brings up the fancy or boring user interface"
}
],
"Dependencies" : [
{ "Name" : "SomeOtherPlugin", "Version" : "2.3.0_2" },
{ "Name" : "EvenOther", "Version" : "1.0.0" }
]
}
\endcode
\section2 A Note on Plugin Versions
Plugin versions are in the form \c{x.y.z_n} where, \c x, \c y, \c z and \c n are
non-negative integer numbers. You don't have to specify the version
in this full form - any left-out part will implicitly be set to zero.
So, \c{2.10_2} is equal to \c{2.10.0_2}, and \c 1 is the same as \c{1.0.0_0}.
*/