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# Application API

Each Sphinx extension is a Python module with at least a `setup()` function. This function is called at initialization time with one argument, the application object representing the Sphinx process.

class `sphinx.application.``Sphinx`

  This application object has the public API described in the following.

## Extension setup

These methods are usually called in an extension’s `setup()` function.

Examples of using the Sphinx extension API can be seen in the `sphinx.ext` package.

`Sphinx.``setup_extension`(name)

  Load the extension given by the module name. Use this if your extension needs the features provided by another extension.

`Sphinx.``add_builder`(builder)

  Register a new builder. builder must be a class that inherits from `Builder`.

`Sphinx.``add_config_value`(name, default, rebuild)

  Register a configuration value. This is necessary for Sphinx to recognize new values and set default values accordingly. The name should be prefixed with the extension name, to avoid clashes. The default value can be any Python object. The string value rebuild must be one of those values:

  - `'env'` if a change in the setting only takes effect when a document is parsed – this means that the whole environment must be rebuilt.
  - `'html'` if a change in the setting needs a full rebuild of HTML documents.
  - `''` if a change in the setting will not need any special rebuild.

  Changed in version 0.4: If the default value is a callable, it will be called with the config object as its argument in order to get the default value. This can be used to implement config values whose default depends on other values.

  Changed in version 0.6: Changed rebuild from a simple boolean (equivalent to `''` or `'env'`) to a string. However, booleans are still accepted and converted internally.

`Sphinx.``add_domain`(domain)

  Make the given domain (which must be a class; more precisely, a subclass of `Domain`) known to Sphinx.

  New in version 1.0.

`Sphinx.``override_domain`(domain)

  Make the given domain class known to Sphinx, assuming that there is already a domain with its `.name`. The new domain must be a subclass of the existing one.

  New in version 1.0.

`Sphinx.``add_index_to_domain`(domain, index)

  Add a custom index class to the domain named domain. index must be a subclass of `Index`.

  New in version 1.0.

`Sphinx.``add_event`(name)

  Register an event called name. This is needed to be able to emit it.

`Sphinx.``set_translator`(name, translator_class)

  Register or override a Docutils translator class. This is used to register a custom output translator or to replace a builtin translator. This allows extensions to use custom translator and define custom nodes for the translator (see `add_node()`).

  This is a API version of `html_translator_class` for all other builders. Note that if `html_translator_class` is specified and this API is called for html related builders, API overriding takes precedence.

  New in version 1.3.

`Sphinx.``add_node`(node, **kwds)

  Register a Docutils node class. This is necessary for Docutils internals. It may also be used in the future to validate nodes in the parsed documents.

  Node visitor functions for the Sphinx HTML, LaTeX, text and manpage writers can be given as keyword arguments: the keyword should be one or more of `'html'`, `'latex'`, `'text'`, `'man'`, `'texinfo'` or any other supported translators, the value a 2-tuple of `(visit, depart)` methods. `depart` can be `None` if the `visit` function raises `docutils.nodes.SkipNode`. Example:

      class math(docutils.nodes.Element): pass

      def visit_math_html(self, node):
          self.body.append(self.starttag(node, 'math'))
      def depart_math_html(self, node):
          self.body.append('</math>')

      app.add_node(math, html=(visit_math_html, depart_math_html))

  Obviously, translators for which you don’t specify visitor methods will choke on the node when encountered in a document to translate.

  Changed in version 0.5: Added the support for keyword arguments giving visit functions.

`Sphinx.``add_enumerable_node`(node, figtype, title_getter=None, **kwds)

  Register a Docutils node class as a numfig target. Sphinx numbers the node automatically. And then the users can refer it using `numref`.

  figtype is a type of enumerable nodes. Each figtypes have individual numbering sequences. As a system figtypes, `figure`, `table` and `code-block` are defined. It is able to add custom nodes to these default figtypes. It is also able to define new custom figtype if new figtype is given.

  title_getter is a getter function to obtain the title of node. It takes an instance of the enumerable node, and it must return its title as string. The title is used to the default title of references for `ref`. By default, Sphinx searches `docutils.nodes.caption` or `docutils.nodes.title` from the node as a title.

  Other keyword arguments are used for node visitor functions. See the `Sphinx.add_node()` for details.

  New in version 1.4.

`Sphinx.``add_directive`(name, func, content, arguments, **options)
`Sphinx.``add_directive`(name, directiveclass)

  Register a Docutils directive. name must be the prospective directive name. There are two possible ways to write a directive:

  - In the docutils 0.4 style, obj is the directive function. content, arguments and options are set as attributes on the function and determine whether the directive has content, arguments and options, respectively. This style is deprecated.

  - In the docutils 0.5 style, directiveclass is the directive class. It must already have attributes named has_content, required_arguments, optional_arguments, final_argument_whitespace and option_spec that correspond to the options for the function way. See the Docutils docs for details.

    The directive class must inherit from the class `docutils.parsers.rst.Directive`.

  For example, the (already existing) `literalinclude` directive would be added like this:

      from docutils.parsers.rst import directives
      add_directive('literalinclude', literalinclude_directive,
                    content = 0, arguments = (1, 0, 0),
                    linenos = directives.flag,
                    language = directives.unchanged,
                    encoding = directives.encoding)

  Changed in version 0.6: Docutils 0.5-style directive classes are now supported.

`Sphinx.``add_directive_to_domain`(domain, name, func, content, arguments, **options)
`Sphinx.``add_directive_to_domain`(domain, name, directiveclass)

  Like `add_directive()`, but the directive is added to the domain named domain.

  New in version 1.0.

`Sphinx.``add_role`(name, role)

  Register a Docutils role. name must be the role name that occurs in the source, role the role function (see the Docutils documentation on details).

`Sphinx.``add_role_to_domain`(domain, name, role)

  Like `add_role()`, but the role is added to the domain named domain.

  New in version 1.0.

`Sphinx.``add_generic_role`(name, nodeclass)

  Register a Docutils role that does nothing but wrap its contents in the node given by nodeclass.

  New in version 0.6.

`Sphinx.``add_object_type`(directivename, rolename, indextemplate='', parse_node=None, ref_nodeclass=None, objname='', doc_field_types=[])

  This method is a very convenient way to add a new object type that can be cross-referenced. It will do this:

  - Create a new directive (called directivename) for documenting an object. It will automatically add index entries if indextemplate is nonempty; if given, it must contain exactly one instance of `%s`. See the example below for how the template will be interpreted.
  - Create a new role (called rolename) to cross-reference to these object descriptions.
  - If you provide parse_node, it must be a function that takes a string and a docutils node, and it must populate the node with children parsed from the string. It must then return the name of the item to be used in cross-referencing and index entries. See the `conf.py` file in the source for this documentation for an example.
  - The objname (if not given, will default to directivename) names the type of object. It is used when listing objects, e.g. in search results.

  For example, if you have this call in a custom Sphinx extension:

      app.add_object_type('directive', 'dir', 'pair: %s; directive')

  you can use this markup in your documents:

      .. rst:directive:: function

         Document a function.

      <...>

      See also the :rst:dir:`function` directive.

  For the directive, an index entry will be generated as if you had prepended

      .. index:: pair: function; directive

  The reference node will be of class `literal` (so it will be rendered in a proportional font, as appropriate for code) unless you give the ref_nodeclass argument, which must be a docutils node class. Most useful are `docutils.nodes.emphasis` or `docutils.nodes.strong` – you can also use `docutils.nodes.generated` if you want no further text decoration. If the text should be treated as literal (e.g. no smart quote replacement), but not have typewriter styling, use `sphinx.addnodes.literal_emphasis` or `sphinx.addnodes.literal_strong`.

  For the role content, you have the same syntactical possibilities as for standard Sphinx roles (see Cross-referencing syntax).

  This method is also available under the deprecated alias `add_description_unit`.

`Sphinx.``add_crossref_type`(directivename, rolename, indextemplate='', ref_nodeclass=None, objname='')

  This method is very similar to `add_object_type()` except that the directive it generates must be empty, and will produce no output.

  That means that you can add semantic targets to your sources, and refer to them using custom roles instead of generic ones (like `ref`). Example call:

      app.add_crossref_type('topic', 'topic', 'single: %s', docutils.nodes.emphasis)

  Example usage:

      .. topic:: application API

      The application API
      -------------------

      <...>

      See also :topic:`this section <application API>`.

  (Of course, the element following the `topic` directive needn’t be a section.)

`Sphinx.``add_transform`(transform)

  Add the standard docutils `Transform` subclass transform to the list of transforms that are applied after Sphinx parses a reST document.

`Sphinx.``add_javascript`(filename)

  Add filename to the list of JavaScript files that the default HTML template will include. The filename must be relative to the HTML static path, see `the docs for the config value`. A full URI with scheme, like `http://example.org/foo.js`, is also supported.

  New in version 0.5.

`Sphinx.``add_stylesheet`(filename)

  Add filename to the list of CSS files that the default HTML template will include. Like for `add_javascript()`, the filename must be relative to the HTML static path, or a full URI with scheme.

  New in version 1.0.

`Sphinx.``add_latex_package`(packagename, options=None)

  Add packagename to the list of packages that LaTeX source code will include. If you provide options, it will be taken to usepackage declaration.

      app.add_latex_package('mypackage')             # => \usepackage{mypackage}
      app.add_latex_package('mypackage', 'foo,bar')  # => \usepackage[foo,bar]{mypackage}

  New in version 1.3.

`Sphinx.``add_lexer`(alias, lexer)

  Use lexer, which must be an instance of a Pygments lexer class, to highlight code blocks with the given language alias.

  New in version 0.6.

`Sphinx.``add_autodocumenter`(cls)

  Add cls as a new documenter class for the `sphinx.ext.autodoc` extension. It must be a subclass of `sphinx.ext.autodoc.Documenter`. This allows to auto-document new types of objects. See the source of the autodoc module for examples on how to subclass `Documenter`.

  New in version 0.6.

`Sphinx.``add_autodoc_attrgetter`(type, getter)

  Add getter, which must be a function with an interface compatible to the `getattr()` builtin, as the autodoc attribute getter for objects that are instances of type. All cases where autodoc needs to get an attribute of a type are then handled by this function instead of `getattr()`.

  New in version 0.6.

`Sphinx.``add_search_language`(cls)

  Add cls, which must be a subclass of `sphinx.search.SearchLanguage`, as a support language for building the HTML full-text search index. The class must have a lang attribute that indicates the language it should be used for. See `html_search_language`.

  New in version 1.1.

`Sphinx.``add_source_parser`(name, suffix, parser)

  Register a parser class for specified suffix.

  New in version 1.4.

`Sphinx.``require_sphinx`(version)

  Compare version (which must be a `major.minor` version string, e.g. `'1.1'`) with the version of the running Sphinx, and abort the build when it is too old.

  New in version 1.0.

`Sphinx.``connect`(event, callback)

  Register callback to be called when event is emitted. For details on available core events and the arguments of callback functions, please see Sphinx core events.

  The method returns a “listener ID” that can be used as an argument to `disconnect()`.

`Sphinx.``disconnect`(listener_id)

  Unregister callback listener_id.

exception `sphinx.application.``ExtensionError`

  All these methods raise this exception if something went wrong with the extension API.

## Emitting events

`Sphinx.``emit`(event, *arguments)

  Emit event and pass arguments to the callback functions. Return the return values of all callbacks as a list. Do not emit core Sphinx events in extensions!

`Sphinx.``emit_firstresult`(event, *arguments)

  Emit event and pass arguments to the callback functions. Return the result of the first callback that doesn’t return `None`.

  New in version 0.5.

## Producing messages / logging

The application object also provides support for emitting leveled messages.

Note

There is no “error” call: in Sphinx, errors are defined as things that stop the build; just raise an exception (`sphinx.errors.SphinxError` or a custom subclass) to do that.

`Sphinx.``warn`(message, location=None, prefix='WARNING: ', type=None, subtype=None)

  Emit a warning.

  If location is given, it should either be a tuple of (docname, lineno) or a string describing the location of the warning as well as possible.

  prefix usually should not be changed.

  type and subtype are used to suppress warnings with `suppress_warnings`.

  Note

  For warnings emitted during parsing, you should use `BuildEnvironment.warn()` since that will collect all warnings during parsing for later output.

`Sphinx.``info`(message='', nonl=False)

  Emit an informational message.

  If nonl is true, don’t emit a newline at the end (which implies that more info output will follow soon.)

`Sphinx.``verbose`(message, *args, **kwargs)

  Emit a verbose informational message.

  The message will only be emitted for verbosity levels >= 1 (i.e. at least one `-v` option was given).

  The message can contain %-style interpolation placeholders, which is formatted with either the `*args` or `**kwargs` when output.

`Sphinx.``debug`(message, *args, **kwargs)

  Emit a debug-level informational message.

  The message will only be emitted for verbosity levels >= 2 (i.e. at least two `-v` options were given).

  The message can contain %-style interpolation placeholders, which is formatted with either the `*args` or `**kwargs` when output.

`Sphinx.``debug2`(message, *args, **kwargs)

  Emit a lowlevel debug-level informational message.

  The message will only be emitted for verbosity level 3 (i.e. three `-v` options were given).

  The message can contain %-style interpolation placeholders, which is formatted with either the `*args` or `**kwargs` when output.

## Sphinx core events

These events are known to the core. The arguments shown are given to the registered event handlers. Use `connect()` in an extension’s `setup` function (note that `conf.py` can also have a `setup` function) to connect handlers to the events. Example:

    def source_read_handler(app, docname, source):
        print('do something here...')

    def setup(app):
        app.connect('source-read', source_read_handler)

`builder-inited`(app)

  Emitted when the builder object has been created. It is available as `app.builder`.

`env-get-outdated`(app, env, added, changed, removed)

  Emitted when the environment determines which source files have changed and should be re-read. added, changed and removed are sets of docnames that the environment has determined. You can return a list of docnames to re-read in addition to these.

  New in version 1.1.

`env-purge-doc`(app, env, docname)

  Emitted when all traces of a source file should be cleaned from the environment, that is, if the source file is removed or before it is freshly read. This is for extensions that keep their own caches in attributes of the environment.

  For example, there is a cache of all modules on the environment. When a source file has been changed, the cache’s entries for the file are cleared, since the module declarations could have been removed from the file.

  New in version 0.5.

`env-before-read-docs`(app, env, docnames)

  Emitted after the environment has determined the list of all added and changed files and just before it reads them. It allows extension authors to reorder the list of docnames (inplace) before processing, or add more docnames that Sphinx did not consider changed (but never add any docnames that are not in `env.found_docs`).

  You can also remove document names; do this with caution since it will make Sphinx treat changed files as unchanged.

  New in version 1.3.

`source-read`(app, docname, source)

  Emitted when a source file has been read. The source argument is a list whose single element is the contents of the source file. You can process the contents and replace this item to implement source-level transformations.

  For example, if you want to use `$` signs to delimit inline math, like in LaTeX, you can use a regular expression to replace `$...$` by `:math:`...``.

  New in version 0.5.

`doctree-read`(app, doctree)

  Emitted when a doctree has been parsed and read by the environment, and is about to be pickled. The doctree can be modified in-place.

`missing-reference`(app, env, node, contnode)

  Emitted when a cross-reference to a Python module or object cannot be resolved. If the event handler can resolve the reference, it should return a new docutils node to be inserted in the document tree in place of the node node. Usually this node is a `reference` node containing contnode as a child.

  Parameters: | env – The build environment (`app.builder.env`). node – The `pending_xref` node to be resolved. Its attributes `reftype`, `reftarget`, `modname` and `classname` attributes determine the type and target of the reference. contnode – The node that carries the text and formatting inside the future reference and should be a child of the returned reference node.

  New in version 0.5.

`doctree-resolved`(app, doctree, docname)

  Emitted when a doctree has been “resolved” by the environment, that is, all references have been resolved and TOCs have been inserted. The doctree can be modified in place.

  Here is the place to replace custom nodes that don’t have visitor methods in the writers, so that they don’t cause errors when the writers encounter them.

`env-merge-info`(env, docnames, other)

  This event is only emitted when parallel reading of documents is enabled. It is emitted once for every subprocess that has read some documents.

  You must handle this event in an extension that stores data in the environment in a custom location. Otherwise the environment in the main process will not be aware of the information stored in the subprocess.

  other is the environment object from the subprocess, env is the environment from the main process. docnames is a set of document names that have been read in the subprocess.

  For a sample of how to deal with this event, look at the standard `sphinx.ext.todo` extension. The implementation is often similar to that of `env-purge-doc`, only that information is not removed, but added to the main environment from the other environment.

  New in version 1.3.

`env-updated`(app, env)

  Emitted when the `update()` method of the build environment has completed, that is, the environment and all doctrees are now up-to-date.

  You can return an iterable of docnames from the handler. These documents will then be considered updated, and will be (re-)written during the writing phase.

  New in version 0.5.

  Changed in version 1.3: The handlers’ return value is now used.

`html-collect-pages`(app)

  Emitted when the HTML builder is starting to write non-document pages. You can add pages to write by returning an iterable from this event consisting of `(pagename, context, templatename)`.

  New in version 1.0.

`html-page-context`(app, pagename, templatename, context, doctree)

  Emitted when the HTML builder has created a context dictionary to render a template with – this can be used to add custom elements to the context.

  The pagename argument is the canonical name of the page being rendered, that is, without `.html` suffix and using slashes as path separators. The templatename is the name of the template to render, this will be `'page.html'` for all pages from reST documents.

  The context argument is a dictionary of values that are given to the template engine to render the page and can be modified to include custom values. Keys must be strings.

  The doctree argument will be a doctree when the page is created from a reST documents; it will be `None` when the page is created from an HTML template alone.

  You can return a string from the handler, it will then replace `'page.html'` as the HTML template for this page.

  New in version 0.4.

  Changed in version 1.3: The return value can now specify a template name.

`build-finished`(app, exception)

  Emitted when a build has finished, before Sphinx exits, usually used for cleanup. This event is emitted even when the build process raised an exception, given as the exception argument. The exception is reraised in the application after the event handlers have run. If the build process raised no exception, exception will be `None`. This allows to customize cleanup actions depending on the exception status.

  New in version 0.5.

## Checking the Sphinx version

Use this to adapt your extension to API changes in Sphinx.

`sphinx.``version_info`

  A tuple of five elements; for Sphinx version 1.2.1 beta 3 this would be `(1, 2, 1, 'beta', 3)`.

  New in version 1.2: Before version 1.2, check the string `sphinx.__version__`.

## The Config object

class `sphinx.config.``Config`

  The config object makes the values of all config values available as attributes.

  It is available as the `config` attribute on the application and environment objects. For example, to get the value of `language`, use either `app.config.language` or `env.config.language`.

## The template bridge

class `sphinx.application.``TemplateBridge`

  This class defines the interface for a “template bridge”, that is, a class that renders templates given a template name and a context.

  `init`(builder, theme=None, dirs=None)

    Called by the builder to initialize the template system.

    builder is the builder object; you’ll probably want to look at the value of `builder.config.templates_path`.

    theme is a `sphinx.theming.Theme` object or None; in the latter case, dirs can be list of fixed directories to look for templates.

  `newest_template_mtime`()

    Called by the builder to determine if output files are outdated because of template changes. Return the mtime of the newest template file that was changed. The default implementation returns `0`.

  `render`(template, context)

    Called by the builder to render a template given as a filename with a specified context (a Python dictionary).

  `render_string`(template, context)

    Called by the builder to render a template given as a string with a specified context (a Python dictionary).

## Exceptions

exception `sphinx.errors.``SphinxError`

  This is the base class for “nice” exceptions. When such an exception is raised, Sphinx will abort the build and present the exception category and message to the user.

  Extensions are encouraged to derive from this exception for their custom errors.

  Exceptions not derived from `SphinxError` are treated as unexpected and shown to the user with a part of the traceback (and the full traceback saved in a temporary file).

  `category`

    Description of the exception “category”, used in converting the exception to a string (“category: message”). Should be set accordingly in subclasses.

exception `sphinx.errors.``ConfigError`

  Used for erroneous values or nonsensical combinations of configuration values.

exception `sphinx.errors.``ExtensionError`

  Used for errors in setting up extensions.

exception `sphinx.errors.``ThemeError`

  Used for errors to do with themes.

exception `sphinx.errors.``VersionRequirementError`

  Raised when the docs require a higher Sphinx version than the current one.