# Domains¶

New in version 1.0.

Originally, Sphinx was conceived for a single project, the documentation of the Python language. Shortly afterwards, it was made available for everyone as a documentation tool, but the documentation of Python modules remained deeply built in – the most fundamental directives, like function, were designed for Python objects. Since Sphinx has become somewhat popular, interest developed in using it for many different purposes: C/C++ projects, JavaScript, or even reStructuredText markup (like in this documentation).

While this was always possible, it is now much easier to easily support documentation of projects using different programming languages or even ones not supported by the main Sphinx distribution, by providing a domain for every such purpose.

A domain is a collection of markup (reStructuredText directives and roles) to describe and link to objects belonging together, e.g. elements of a programming language. Directive and role names in a domain have names like domain:name, e.g. py:function. Domains can also provide custom indices (like the Python Module Index).

Having domains means that there are no naming problems when one set of documentation wants to refer to e.g. C++ and Python classes. It also means that extensions that support the documentation of whole new languages are much easier to write.

This section describes what the domains that are included with Sphinx provide. The domain API is documented as well, in the section Domain API.

## Basic Markup¶

Most domains provide a number of object description directives, used to describe specific objects provided by modules. Each directive requires one or more signatures to provide basic information about what is being described, and the content should be the description. A domain will typically keep an internal index of all entites to aid cross-referencing. Typically it will also add entries in the shown general index. If you want to suppress the addition of an entry in the shown index, you can give the directive option flag :noindexentry:. If you want to typeset an object description, without even making it available for cross-referencing, you can give the directive option flag :noindex: (which implies :noindexentry:). Though, note that not every directive en every domain may support these options.

New in version 3.2: The directive option noindexentry in the Python, C, C++, and Javascript domains.

An example using a Python domain directive:

.. py:function:: spam(eggs)
ham(eggs)

Spam or ham the foo.


This describes the two Python functions spam and ham. (Note that when signatures become too long, you can break them if you add a backslash to lines that are continued in the next line. Example:

.. py:function:: filterwarnings(action, message='', category=Warning, \
module='', lineno=0, append=False)
:noindex:


(This example also shows how to use the :noindex: flag.)

The domains also provide roles that link back to these object descriptions. For example, to link to one of the functions described in the example above, you could say

The function :py:func:spam does a similar thing.


As you can see, both directive and role names contain the domain name and the directive name.

Default Domain

For documentation describing objects from solely one domain, authors will not have to state again its name at each directive, role, etc… after having specified a default. This can be done either via the config value primary_domain or via this directive:

.. default-domain:: name

Select a new default domain. While the primary_domain selects a global default, this only has an effect within the same file.

If no other default is selected, the Python domain (named py) is the default one, mostly for compatibility with documentation written for older versions of Sphinx.

Directives and roles that belong to the default domain can be mentioned without giving the domain name, i.e.

.. function:: pyfunc()

Describes a Python function.

Reference to :func:pyfunc.


### Cross-referencing syntax¶

For cross-reference roles provided by domains, the same facilities exist as for general cross-references. See Cross-referencing syntax.

In short:

• You may supply an explicit title and reference target: :role:title <target> will refer to target, but the link text will be title.

• If you prefix the content with !, no reference/hyperlink will be created.

• If you prefix the content with ~, the link text will only be the last component of the target. For example, :py:meth:~Queue.Queue.get will refer to Queue.Queue.get but only display get as the link text.

## The Python Domain¶

The Python domain (name py) provides the following directives for module declarations:

.. py:module:: name

This directive marks the beginning of the description of a module (or package submodule, in which case the name should be fully qualified, including the package name). It does not create content (like e.g. py:class does).

This directive will also cause an entry in the global module index.

options

:platform: platforms (comma separated list)

Indicate platforms which the module is available (if it is available on all platforms, the option should be omitted). The keys are short identifiers; examples that are in use include “IRIX”, “Mac”, “Windows” and “Unix”. It is important to use a key which has already been used when applicable.

:synopsis: purpose (text)

Consist of one sentence describing the module’s purpose – it is currently only used in the Global Module Index.

:deprecated: (no argument)

Mark a module as deprecated; it will be designated as such in various locations then.

.. py:currentmodule:: name

This directive tells Sphinx that the classes, functions etc. documented from here are in the given module (like py:module), but it will not create index entries, an entry in the Global Module Index, or a link target for py:mod. This is helpful in situations where documentation for things in a module is spread over multiple files or sections – one location has the py:module directive, the others only py:currentmodule.

The following directives are provided for module and class contents:

.. py:function:: name(parameters)

Describes a module-level function. The signature should include the parameters as given in the Python function definition, see Python Signatures. For example:

.. py:function:: Timer.repeat(repeat=3, number=1000000)


For methods you should use py:method.

The description normally includes information about the parameters required and how they are used (especially whether mutable objects passed as parameters are modified), side effects, and possible exceptions.

This information can (in any py directive) optionally be given in a structured form, see Info field lists.

options

:async: (no value)

Indicate the function is an async function.

New in version 2.1.

:canonical: (full qualified name including module name)

Describe the location where the object is defined if the object is imported from other modules

New in version 4.0.

.. py:data:: name

Describes global data in a module, including both variables and values used as “defined constants.” Class and object attributes are not documented using this environment.

options

:type: type of the variable (text)

New in version 2.4.

:value: initial value of the variable (text)

New in version 2.4.

:canonical: (full qualified name including module name)

Describe the location where the object is defined if the object is imported from other modules

New in version 4.0.

.. py:exception:: name

Describes an exception class. The signature can, but need not include parentheses with constructor arguments.

options

:final: (no value)

Indicate the class is a final class.

New in version 3.1.

.. py:class:: name
.. py:class:: name(parameters)

Describes a class. The signature can optionally include parentheses with parameters which will be shown as the constructor arguments. See also Python Signatures.

Methods and attributes belonging to the class should be placed in this directive’s body. If they are placed outside, the supplied name should contain the class name so that cross-references still work. Example:

.. py:class:: Foo

.. py:method:: quux()

-- or --

.. py:class:: Bar

.. py:method:: Bar.quux()


The first way is the preferred one.

options

:canonical: (full qualified name including module name)

Describe the location where the object is defined if the object is imported from other modules

New in version 4.0.

:final: (no value)

Indicate the class is a final class.

New in version 3.1.

.. py:attribute:: name

Describes an object data attribute. The description should include information about the type of the data to be expected and whether it may be changed directly.

options

:type: type of the attribute (text)

New in version 2.4.

:value: initial value of the attribute (text)

New in version 2.4.

:canonical: (full qualified name including module name)

Describe the location where the object is defined if the object is imported from other modules

New in version 4.0.

.. py:method:: name(parameters)

Describes an object method. The parameters should not include the self parameter. The description should include similar information to that described for function. See also Python Signatures and Info field lists.

options

:abstractmethod: (no value)

Indicate the method is an abstract method.

New in version 2.1.

:async: (no value)

Indicate the method is an async method.

New in version 2.1.

:canonical: (full qualified name including module name)

Describe the location where the object is defined if the object is imported from other modules

New in version 4.0.

:classmethod: (no value)

Indicate the method is a class method.

New in version 2.1.

:final: (no value)

Indicate the class is a final method.

New in version 3.1.

:property: (no value)

Indicate the method is a property.

New in version 2.1.

:staticmethod: (no value)

Indicate the method is a static method.

New in version 2.1.

.. py:staticmethod:: name(parameters)

Like py:method, but indicates that the method is a static method.

New in version 0.4.

.. py:classmethod:: name(parameters)

Like py:method, but indicates that the method is a class method.

New in version 0.6.

.. py:decorator:: name
.. py:decorator:: name(parameters)

Describes a decorator function. The signature should represent the usage as a decorator. For example, given the functions

def removename(func):
func.__name__ = ''
return func

def setnewname(name):
def decorator(func):
func.__name__ = name
return func
return decorator


the descriptions should look like this:

.. py:decorator:: removename

Remove name of the decorated function.

.. py:decorator:: setnewname(name)

Set name of the decorated function to *name*.


(as opposed to .. py:decorator:: removename(func).)

There is no py:deco role to link to a decorator that is marked up with this directive; rather, use the py:func role.

.. py:decoratormethod:: name
.. py:decoratormethod:: name(signature)

Same as py:decorator, but for decorators that are methods.

Refer to a decorator method using the py:meth role.

### Python Signatures¶

Signatures of functions, methods and class constructors can be given like they would be written in Python.

Default values for optional arguments can be given (but if they contain commas, they will confuse the signature parser). Python 3-style argument annotations can also be given as well as return type annotations:

.. py:function:: compile(source : string, filename, symbol='file') -> ast object


For functions with optional parameters that don’t have default values (typically functions implemented in C extension modules without keyword argument support), you can use brackets to specify the optional parts:

compile(source[, filename[, symbol]])

It is customary to put the opening bracket before the comma.

### Info field lists¶

New in version 0.4.

Changed in version 3.0: meta fields are added.

Inside Python object description directives, reST field lists with these fields are recognized and formatted nicely:

• param, parameter, arg, argument, key, keyword: Description of a parameter.

• type: Type of a parameter. Creates a link if possible.

• raises, raise, except, exception: That (and when) a specific exception is raised.

• var, ivar, cvar: Description of a variable.

• vartype: Type of a variable. Creates a link if possible.

• returns, return: Description of the return value.

• rtype: Return type. Creates a link if possible.

• meta: Add metadata to description of the python object. The metadata will not be shown on output document. For example, :meta private: indicates the python object is private member. It is used in sphinx.ext.autodoc for filtering members.

Note

In current release, all var, ivar and cvar are represented as “Variable”. There is no difference at all.

The field names must consist of one of these keywords and an argument (except for returns and rtype, which do not need an argument). This is best explained by an example:

.. py:function:: send_message(sender, recipient, message_body, [priority=1])

Send a message to a recipient

:param str sender: The person sending the message
:param str recipient: The recipient of the message
:param str message_body: The body of the message
:param priority: The priority of the message, can be a number 1-5
:type priority: integer or None
:return: the message id
:rtype: int
:raises ValueError: if the message_body exceeds 160 characters
:raises TypeError: if the message_body is not a basestring


This will render like this:

send_message(sender, recipient, message_body[, priority=1])

Send a message to a recipient

Parameters
• sender (str) – The person sending the message

• recipient (str) – The recipient of the message

• message_body (str) – The body of the message

• priority (integer or None) – The priority of the message, can be a number 1-5

Returns

the message id

Return type

int

Raises
• ValueError – if the message_body exceeds 160 characters

• TypeError – if the message_body is not a basestring

It is also possible to combine parameter type and description, if the type is a single word, like this:

:param int priority: The priority of the message, can be a number 1-5


New in version 1.5.

Container types such as lists and dictionaries can be linked automatically using the following syntax:

:type priorities: list(int)
:type priorities: list[int]
:type mapping: dict(str, int)
:type mapping: dict[str, int]
:type point: tuple(float, float)
:type point: tuple[float, float]


Multiple types in a type field will be linked automatically if separated by the word “or”:

:type an_arg: int or None
:vartype a_var: str or int
:rtype: float or str


### Cross-referencing Python objects¶

The following roles refer to objects in modules and are possibly hyperlinked if a matching identifier is found:

:py:mod:

Reference a module; a dotted name may be used. This should also be used for package names.

:py:func:

Reference a Python function; dotted names may be used. The role text needs not include trailing parentheses to enhance readability; they will be added automatically by Sphinx if the add_function_parentheses config value is True (the default).

:py:data:

Reference a module-level variable.

:py:const:

Reference a “defined” constant. This may be a Python variable that is not intended to be changed.

:py:class:

Reference a class; a dotted name may be used.

:py:meth:

Reference a method of an object. The role text can include the type name and the method name; if it occurs within the description of a type, the type name can be omitted. A dotted name may be used.

:py:attr:

Reference a data attribute of an object.

:py:exc:

Reference an exception. A dotted name may be used.

:py:obj:

Reference an object of unspecified type. Useful e.g. as the default_role.

New in version 0.4.

The name enclosed in this markup can include a module name and/or a class name. For example, :py:func:filter could refer to a function named filter in the current module, or the built-in function of that name. In contrast, :py:func:foo.filter clearly refers to the filter function in the foo module.

Normally, names in these roles are searched first without any further qualification, then with the current module name prepended, then with the current module and class name (if any) prepended. If you prefix the name with a dot, this order is reversed. For example, in the documentation of Python’s codecs module, :py:func:open always refers to the built-in function, while :py:func:.open refers to codecs.open().

A similar heuristic is used to determine whether the name is an attribute of the currently documented class.

Also, if the name is prefixed with a dot, and no exact match is found, the target is taken as a suffix and all object names with that suffix are searched. For example, :py:meth:.TarFile.close references the tarfile.TarFile.close() function, even if the current module is not tarfile. Since this can get ambiguous, if there is more than one possible match, you will get a warning from Sphinx.

Note that you can combine the ~ and . prefixes: :py:meth:~.TarFile.close will reference the tarfile.TarFile.close() method, but the visible link caption will only be close().

## The C Domain¶

The C domain (name c) is suited for documentation of C API.

.. c:member:: declaration
.. c:var:: declaration

Describes a C struct member or variable. Example signature:

.. c:member:: PyObject *PyTypeObject.tp_bases


The difference between the two directives is only cosmetic.

.. c:function:: function prototype

Describes a C function. The signature should be given as in C, e.g.:

.. c:function:: PyObject *PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)


Note that you don’t have to backslash-escape asterisks in the signature, as it is not parsed by the reST inliner.

.. c:macro:: name
.. c:macro:: name(arg list)

Describes a C macro, i.e., a C-language #define, without the replacement text.

New in version 3.0: The function style variant.

.. c:struct:: name

Describes a C struct.

New in version 3.0.

.. c:union:: name

Describes a C union.

New in version 3.0.

.. c:enum:: name

Describes a C enum.

New in version 3.0.

.. c:enumerator:: name

Describes a C enumerator.

New in version 3.0.

.. c:type:: typedef-like declaration
.. c:type:: name

Describes a C type, either as a typedef, or the alias for an unspecified type.

### Cross-referencing C constructs¶

The following roles create cross-references to C-language constructs if they are defined in the documentation:

:c:member:
:c:data:
:c:var:
:c:func:
:c:macro:
:c:struct:
:c:union:
:c:enum:
:c:enumerator:
:c:type:

Reference a C declaration, as defined above. Note that c:member, c:data, and c:var are equivalent.

New in version 3.0: The var, struct, union, enum, and enumerator roles.

### Anonymous Entities¶

C supports anonymous structs, enums, and unions. For the sake of documentation they must be given some name that starts with @, e.g., @42 or @data. These names can also be used in cross-references, though nested symbols will be found even when omitted. The @... name will always be rendered as [anonymous] (possibly as a link).

Example:

.. c:struct:: Data

.. c:union:: @data

.. c:var:: int a

.. c:var:: double b

Explicit ref: :c:var:Data.@data.a. Short-hand ref: :c:var:Data.a.


This will be rendered as:

struct Data
union [anonymous]
int a
double b

Explicit ref: Data.[anonymous].a. Short-hand ref: Data.a.

New in version 3.0.

### Aliasing Declarations¶

Sometimes it may be helpful list declarations elsewhere than their main documentation, e.g., when creating a synopsis of an interface. The following directive can be used for this purpose.

.. c:alias:: name

Insert one or more alias declarations. Each entity can be specified as they can in the c:any role.

For example:

.. c:var:: int data
.. c:function:: int f(double k)

.. c:alias:: data
f


becomes

int data
int f(double k)
int data
int f(double k)

New in version 3.2.

### Inline Expressions and Types¶

:c:expr:
:c:texpr:

Insert a C expression or type either as inline code (cpp:expr) or inline text (cpp:texpr). For example:

.. c:var:: int a = 42

.. c:function:: int f(int i)

An expression: :c:expr:a * f(a) (or as text: :c:texpr:a * f(a)).

A type: :c:expr:const Data*
(or as text :c:texpr:const Data*).


will be rendered as follows:

int a = 42
int f(int i)

An expression: a * f(a) (or as text: a * f(a)).

A type: const Data* (or as text const Data*).

New in version 3.0.

### Namespacing¶

New in version 3.1.

The C language it self does not support namespacing, but it can sometimes be useful to emulate it in documentation, e.g., to show alternate declarations. The feature may also be used to document members of structs/unions/enums separate from their parent declaration.

The current scope can be changed using three namespace directives. They manage a stack declarations where c:namespace resets the stack and changes a given scope.

The c:namespace-push directive changes the scope to a given inner scope of the current one.

The c:namespace-pop directive undoes the most recent c:namespace-push directive.

.. c:namespace:: scope specification

Changes the current scope for the subsequent objects to the given scope, and resets the namespace directive stack. Note that nested scopes can be specified by separating with a dot, e.g.:

.. c:namespace:: Namespace1.Namespace2.SomeStruct.AnInnerStruct


All subsequent objects will be defined as if their name were declared with the scope prepended. The subsequent cross-references will be searched for starting in the current scope.

Using NULL or 0 as the scope will change to global scope.

.. c:namespace-push:: scope specification

Change the scope relatively to the current scope. For example, after:

.. c:namespace:: A.B

.. c:namespace-push:: C.D


the current scope will be A.B.C.D.

.. c:namespace-pop::

Undo the previous c:namespace-push directive (not just pop a scope). For example, after:

.. c:namespace:: A.B

.. c:namespace-push:: C.D

.. c:namespace-pop::


the current scope will be A.B (not A.B.C).

If no previous c:namespace-push directive has been used, but only a c:namespace directive, then the current scope will be reset to global scope. That is, .. c:namespace:: A.B is equivalent to:

.. c:namespace:: NULL

.. c:namespace-push:: A.B


## The C++ Domain¶

The C++ domain (name cpp) supports documenting C++ projects.

### Directives for Declaring Entities¶

The following directives are available. All declarations can start with a visibility statement (public, private or protected).

.. cpp:class:: class specifier
.. cpp:struct:: class specifier

Describe a class/struct, possibly with specification of inheritance, e.g.,:

.. cpp:class:: MyClass : public MyBase, MyOtherBase


The difference between cpp:class and cpp:struct is only cosmetic: the prefix rendered in the output, and the specifier shown in the index.

The class can be directly declared inside a nested scope, e.g.,:

.. cpp:class:: OuterScope::MyClass : public MyBase, MyOtherBase


A class template can be declared:

.. cpp:class:: template<typename T, std::size_t N> std::array


or with a line break:

.. cpp:class:: template<typename T, std::size_t N> \
std::array


Full and partial template specialisations can be declared:

.. cpp:class:: template<> \
std::array<bool, 256>

.. cpp:class:: template<typename T> \
std::array<T, 42>


New in version 2.0: The cpp:struct directive.

.. cpp:function:: (member) function prototype

Describe a function or member function, e.g.,:

.. cpp:function:: bool myMethod(int arg1, std::string arg2)

A function with parameters and types.

.. cpp:function:: bool myMethod(int, double)

A function with unnamed parameters.

.. cpp:function:: const T &MyClass::operator[](std::size_t i) const

An overload for the indexing operator.

.. cpp:function:: operator bool() const

A casting operator.

.. cpp:function:: constexpr void foo(std::string &bar[2]) noexcept

A constexpr function.

.. cpp:function:: MyClass::MyClass(const MyClass&) = default

A copy constructor with default implementation.


Function templates can also be described:

.. cpp:function:: template<typename U> \
void print(U &&u)


and function template specialisations:

.. cpp:function:: template<> \
void print(int i)

.. cpp:member:: (member) variable declaration
.. cpp:var:: (member) variable declaration

Describe a variable or member variable, e.g.,:

.. cpp:member:: std::string MyClass::myMember

.. cpp:var:: std::string MyClass::myOtherMember[N][M]

.. cpp:member:: int a = 42


Variable templates can also be described:

.. cpp:member:: template<class T> \
constexpr T pi = T(3.1415926535897932385)

.. cpp:type:: typedef declaration
.. cpp:type:: name
.. cpp:type:: type alias declaration

Describe a type as in a typedef declaration, a type alias declaration, or simply the name of a type with unspecified type, e.g.,:

.. cpp:type:: std::vector<int> MyList

A typedef-like declaration of a type.

.. cpp:type:: MyContainer::const_iterator

Declaration of a type alias with unspecified type.

.. cpp:type:: MyType = std::unordered_map<int, std::string>

Declaration of a type alias.


A type alias can also be templated:

.. cpp:type:: template<typename T> \
MyContainer = std::vector<T>


The example are rendered as follows.

typedef std::vector<int> MyList

A typedef-like declaration of a type.

type MyContainer::const_iterator

Declaration of a type alias with unspecified type.

using MyType = std::unordered_map<int, std::string>

Declaration of a type alias.

template<typename T>
using MyContainer = std::vector<T>
.. cpp:enum:: unscoped enum declaration
.. cpp:enum-struct:: scoped enum declaration
.. cpp:enum-class:: scoped enum declaration

Describe a (scoped) enum, possibly with the underlying type specified. Any enumerators declared inside an unscoped enum will be declared both in the enum scope and in the parent scope. Examples:

.. cpp:enum:: MyEnum

An unscoped enum.

.. cpp:enum:: MySpecificEnum : long

An unscoped enum with specified underlying type.

.. cpp:enum-class:: MyScopedEnum

A scoped enum.

.. cpp:enum-struct:: protected MyScopedVisibilityEnum : std::underlying_type<MySpecificEnum>::type

A scoped enum with non-default visibility, and with a specified
underlying type.

.. cpp:enumerator:: name
.. cpp:enumerator:: name = constant

Describe an enumerator, optionally with its value defined, e.g.,:

.. cpp:enumerator:: MyEnum::myEnumerator

.. cpp:enumerator:: MyEnum::myOtherEnumerator = 42

.. cpp:union:: name

Describe a union.

New in version 1.8.

.. cpp:concept:: template-parameter-list name

Warning

The support for concepts is experimental. It is based on the current draft standard and the Concepts Technical Specification. The features may change as they evolve.

Describe a concept. It must have exactly 1 template parameter list. The name may be a nested name. Example:

.. cpp:concept:: template<typename It> std::Iterator

Proxy to an element of a notional sequence that can be compared,
indirected, or incremented.

**Notation**

.. cpp:var:: It r

An lvalue.

**Valid Expressions**

- :cpp:expr:*r, when :cpp:expr:r is dereferenceable.
- :cpp:expr:++r, with return type :cpp:expr:It&, when
:cpp:expr:r is incrementable.


This will render as follows:

template<typename It>
concept std::Iterator

Proxy to an element of a notional sequence that can be compared, indirected, or incremented.

Notation

It r

An lvalue.

Valid Expressions

• *r, when r is dereferenceable.

• ++r, with return type It&, when r is incrementable.

New in version 1.5.

#### Options¶

Some directives support options:

• :noindexentry:, see Basic Markup.

• :tparam-line-spec:, for templated declarations. If specified, each template parameter will be rendered on a separate line.

New in version 1.6.

### Anonymous Entities¶

C++ supports anonymous namespaces, classes, enums, and unions. For the sake of documentation they must be given some name that starts with @, e.g., @42 or @data. These names can also be used in cross-references and (type) expressions, though nested symbols will be found even when omitted. The @... name will always be rendered as [anonymous] (possibly as a link).

Example:

.. cpp:class:: Data

.. cpp:union:: @data

.. cpp:var:: int a

.. cpp:var:: double b

Explicit ref: :cpp:var:Data::@data::a. Short-hand ref: :cpp:var:Data::a.


This will be rendered as:

class Data
union [anonymous]
int a
double b

Explicit ref: Data::[anonymous]::a. Short-hand ref: Data::a.

New in version 1.8.

### Aliasing Declarations¶

Sometimes it may be helpful list declarations elsewhere than their main documentation, e.g., when creating a synopsis of a class interface. The following directive can be used for this purpose.

.. cpp:alias:: name or function signature

Insert one or more alias declarations. Each entity can be specified as they can in the cpp:any role. If the name of a function is given (as opposed to the complete signature), then all overloads of the function will be listed.

For example:

.. cpp:alias:: Data::a


becomes

int a
void f(double d) const
void f(double d)
void f(int i)
void f()

whereas:

.. cpp:alias:: void overload_example::C::f(double d) const


becomes

void f(double d) const
void f(double d)

New in version 2.0.

### Constrained Templates¶

Warning

The support for concepts is experimental. It is based on the current draft standard and the Concepts Technical Specification. The features may change as they evolve.

Note

Sphinx does not currently support requires clauses.

#### Placeholders¶

Declarations may use the name of a concept to introduce constrained template parameters, or the keyword auto to introduce unconstrained template parameters:

.. cpp:function:: void f(auto &&arg)

A function template with a single unconstrained template parameter.

.. cpp:function:: void f(std::Iterator it)

A function template with a single template parameter, constrained by the
Iterator concept.


#### Template Introductions¶

Simple constrained function or class templates can be declared with a template introduction instead of a template parameter list:

.. cpp:function:: std::Iterator{It} void advance(It &it)

A function template with a template parameter constrained to be an
Iterator.

.. cpp:class:: std::LessThanComparable{T} MySortedContainer

A class template with a template parameter constrained to be
LessThanComparable.


They are rendered as follows.

std::Iterator{It}
void advance(It &it)

A function template with a template parameter constrained to be an Iterator.

std::LessThanComparable{T}
class MySortedContainer

A class template with a template parameter constrained to be LessThanComparable.

Note however that no checking is performed with respect to parameter compatibility. E.g., Iterator{A, B, C} will be accepted as an introduction even though it would not be valid C++.

### Inline Expressions and Types¶

:cpp:expr:
:cpp:texpr:

Insert a C++ expression or type either as inline code (cpp:expr) or inline text (cpp:texpr). For example:

.. cpp:var:: int a = 42

.. cpp:function:: int f(int i)

An expression: :cpp:expr:a * f(a) (or as text: :cpp:texpr:a * f(a)).

A type: :cpp:expr:const MySortedContainer<int>&
(or as text :cpp:texpr:const MySortedContainer<int>&).


will be rendered as follows:

int a = 42
int f(int i)

An expression: a * f(a) (or as text: a * f(a)).

A type: const MySortedContainer<int>& (or as text const MySortedContainer<int>&).

New in version 1.7: The cpp:expr role.

New in version 1.8: The cpp:texpr role.

### Namespacing¶

Declarations in the C++ domain are as default placed in global scope. The current scope can be changed using three namespace directives. They manage a stack declarations where cpp:namespace resets the stack and changes a given scope.

The cpp:namespace-push directive changes the scope to a given inner scope of the current one.

The cpp:namespace-pop directive undoes the most recent cpp:namespace-push directive.

.. cpp:namespace:: scope specification

Changes the current scope for the subsequent objects to the given scope, and resets the namespace directive stack. Note that the namespace does not need to correspond to C++ namespaces, but can end in names of classes, e.g.,:

.. cpp:namespace:: Namespace1::Namespace2::SomeClass::AnInnerClass


All subsequent objects will be defined as if their name were declared with the scope prepended. The subsequent cross-references will be searched for starting in the current scope.

Using NULL, 0, or nullptr as the scope will change to global scope.

A namespace declaration can also be templated, e.g.,:

.. cpp:class:: template<typename T> \
std::vector

.. cpp:namespace:: template<typename T> std::vector

.. cpp:function:: std::size_t size() const


declares size as a member function of the class template std::vector. Equivalently this could have been declared using:

.. cpp:class:: template<typename T> \
std::vector

.. cpp:function:: std::size_t size() const


or:

.. cpp:class:: template<typename T> \
std::vector

.. cpp:namespace-push:: scope specification

Change the scope relatively to the current scope. For example, after:

.. cpp:namespace:: A::B

.. cpp:namespace-push:: C::D


the current scope will be A::B::C::D.

New in version 1.4.

.. cpp:namespace-pop::

Undo the previous cpp:namespace-push directive (not just pop a scope). For example, after:

.. cpp:namespace:: A::B

.. cpp:namespace-push:: C::D

.. cpp:namespace-pop::


the current scope will be A::B (not A::B::C).

If no previous cpp:namespace-push directive has been used, but only a cpp:namespace directive, then the current scope will be reset to global scope. That is, .. cpp:namespace:: A::B is equivalent to:

.. cpp:namespace:: nullptr

.. cpp:namespace-push:: A::B


New in version 1.4.

### Info field lists¶

The C++ directives support the following info fields (see also Info field lists):

• param, parameter, arg, argument: Description of a parameter.

• tparam: Description of a template parameter.

• returns, return: Description of a return value.

• throws, throw, exception: Description of a possibly thrown exception.

### Cross-referencing¶

These roles link to the given declaration types:

:cpp:any:
:cpp:class:
:cpp:struct:
:cpp:func:
:cpp:member:
:cpp:var:
:cpp:type:
:cpp:concept:
:cpp:enum:
:cpp:enumerator:

Reference a C++ declaration by name (see below for details). The name must be properly qualified relative to the position of the link.

New in version 2.0: The cpp:struct role as alias for the cpp:class role.

Note on References with Templates Parameters/Arguments

These roles follow the Sphinx Cross-referencing syntax rules. This means care must be taken when referencing a (partial) template specialization, e.g. if the link looks like this: :cpp:class:MyClass<int>. This is interpreted as a link to int with a title of MyClass. In this case, escape the opening angle bracket with a backslash, like this: :cpp:class:MyClass\<int>.

When a custom title is not needed it may be useful to use the roles for inline expressions, cpp:expr and cpp:texpr, where angle brackets do not need escaping.

#### Declarations without template parameters and template arguments¶

For linking to non-templated declarations the name must be a nested name, e.g., f or MyClass::f.

When a (member) function is referenced using just its name, the reference will point to an arbitrary matching overload. The cpp:any and cpp:func roles use an alternative format, which simply is a complete function declaration. This will resolve to the exact matching overload. As example, consider the following class declaration:

class C
void f(double d) const
void f(double d)
void f(int i)
void f()

References using the cpp:func role:

Note that the add_function_parentheses configuration variable does not influence specific overload references.

#### Templated declarations¶

Assume the following declarations.

class Wrapper
template<typename TOuter>
class Outer
template<typename TInner>
class Inner

In general the reference must include the template parameter declarations, and template arguments for the prefix of qualified names. For example:

• template\<typename TOuter> Wrapper::Outer (template<typename TOuter> Wrapper::Outer)

• template\<typename TOuter> template\<typename TInner> Wrapper::Outer<TOuter>::Inner (template<typename TOuter> template<typename TInner> Wrapper::Outer<TOuter>::Inner)

Currently the lookup only succeed if the template parameter identifiers are equal strings. That is, template\<typename UOuter> Wrapper::Outer will not work.

As a shorthand notation, if a template parameter list is omitted, then the lookup will assume either a primary template or a non-template, but not a partial template specialisation. This means the following references work as well:

#### (Full) Template Specialisations¶

Assume the following declarations.

template<typename TOuter>
class Outer
template<typename TInner>
class Inner
template<>
class Outer<int>
template<typename TInner>
class Inner
template<>
class Inner<bool>

In general the reference must include a template parameter list for each template argument list. The full specialisation above can therefore be referenced with template\<> Outer\<int> (template<> Outer<int>) and template\<> template\<> Outer\<int>::Inner\<bool> (template<> template<> Outer<int>::Inner<bool>). As a shorthand the empty template parameter list can be omitted, e.g., Outer\<int> (Outer<int>) and Outer\<int>::Inner\<bool> (Outer<int>::Inner<bool>).

#### Partial Template Specialisations¶

Assume the following declaration.

template<typename T>
class Outer<T*>

References to partial specialisations must always include the template parameter lists, e.g., template\<typename T> Outer\<T*> (template<typename T> Outer<T*>). Currently the lookup only succeed if the template parameter identifiers are equal strings.

## The Standard Domain¶

The so-called “standard” domain collects all markup that doesn’t warrant a domain of its own. Its directives and roles are not prefixed with a domain name.

The standard domain is also where custom object descriptions, added using the add_object_type() API, are placed.

There is a set of directives allowing documenting command-line programs:

.. option:: name args, name args, ...

Describes a command line argument or switch. Option argument names should be enclosed in angle brackets. Examples:

.. option:: dest_dir

Destination directory.

.. option:: -m <module>, --module <module>

Run a module as a script.


The directive will create cross-reference targets for the given options, referenceable by option (in the example case, you’d use something like :option:dest_dir, :option:-m, or :option:--module).

cmdoption directive is a deprecated alias for the option directive.

.. envvar:: name

Describes an environment variable that the documented code or program uses or defines. Referenceable by envvar.

.. program:: name

Like py:currentmodule, this directive produces no output. Instead, it serves to notify Sphinx that all following option directives document options for the program called name.

If you use program, you have to qualify the references in your option roles by the program name, so if you have the following situation

.. program:: rm

.. option:: -r

Work recursively.

.. program:: svn

.. option:: -r revision

Specify the revision to work upon.


then :option:rm -r would refer to the first option, while :option:svn -r would refer to the second one.

The program name may contain spaces (in case you want to document subcommands like svn add and svn commit separately).

New in version 0.5.

There is also a very generic object description directive, which is not tied to any domain:

.. describe:: text
.. object:: text

This directive produces the same formatting as the specific ones provided by domains, but does not create index entries or cross-referencing targets. Example:

.. describe:: PAPER

You can set this variable to select a paper size.


## The JavaScript Domain¶

The JavaScript domain (name js) provides the following directives:

.. js:module:: name

This directive sets the module name for object declarations that follow after. The module name is used in the global module index and in cross references. This directive does not create an object heading like py:class would, for example.

By default, this directive will create a linkable entity and will cause an entry in the global module index, unless the noindex option is specified. If this option is specified, the directive will only update the current module name.

New in version 1.6.

.. js:function:: name(signature)

Describes a JavaScript function or method. If you want to describe arguments as optional use square brackets as documented for Python signatures.

You can use fields to give more details about arguments and their expected types, errors which may be thrown by the function, and the value being returned:

.. js:function:: $.getJSON(href, callback[, errback]) :param string href: An URI to the location of the resource. :param callback: Gets called with the object. :param errback: Gets called in case the request fails. And a lot of other text so we need multiple lines. :throws SomeError: For whatever reason in that case. :returns: Something.  This is rendered as: $.getJSON(href, callback[, errback])
Arguments
• href (string) – An URI to the location of the resource.

• callback – Gets called with the object.

• errback – Gets called in case the request fails. And a lot of other text so we need multiple lines.

Throws

SomeError – For whatever reason in that case.

Returns

Something.

.. js:method:: name(signature)

This directive is an alias for js:function, however it describes a function that is implemented as a method on a class object.

New in version 1.6.

.. js:class:: name

Describes a constructor that creates an object. This is basically like a function but will show up with a class prefix:

.. js:class:: MyAnimal(name[, age])

:param string name: The name of the animal
:param number age: an optional age for the animal


This is rendered as:

class MyAnimal(name[, age])
Arguments
• name (string) – The name of the animal

• age (number) – an optional age for the animal

.. js:data:: name

Describes a global variable or constant.

.. js:attribute:: object.name

Describes the attribute name of object.

These roles are provided to refer to the described objects:

:js:mod:
:js:func:
:js:meth:
:js:class:
:js:data:
:js:attr:

## The reStructuredText domain¶

The reStructuredText domain (name rst) provides the following directives:

.. rst:directive:: name

Describes a reST directive. The name can be a single directive name or actual directive syntax (.. prefix and :: suffix) with arguments that will be rendered differently. For example:

.. rst:directive:: foo

Foo description.

.. rst:directive:: .. bar:: baz

Bar description.


will be rendered as:

.. foo::

Foo description.

.. bar:: baz

Bar description.

.. rst:directive:option:: name

Describes an option for reST directive. The name can be a single option name or option name with arguments which separated with colon (:). For example:

.. rst:directive:: toctree

.. rst:directive:option:: caption: caption of ToC

.. rst:directive:option:: glob


will be rendered as:

.. toctree::
:caption: caption of ToC
:glob:

options

:type: description of argument (text)

Describe the type of option value.

For example:

.. rst:directive:: toctree

.. rst:directive:option:: maxdepth
:type: integer or no value


New in version 2.1.

.. rst:role:: name

Describes a reST role. For example:

.. rst:role:: foo

Foo description.


will be rendered as:

:foo:

Foo description.

These roles are provided to refer to the described objects:

:rst:dir:
:rst:role:

## The Math Domain¶

The math domain (name math) provides the following roles:

:math:numref:

Role for cross-referencing equations defined by math directive via their label. Example:

.. math:: e^{i\pi} + 1 = 0
:label: euler

Euler's identity, equation :math:numref:euler, was elected one of the
most beautiful mathematical formulas.


New in version 1.8.

## More domains¶

The sphinx-contrib repository contains more domains available as extensions; currently Ada, CoffeeScript, Erlang, HTTP, Lasso, MATLAB, PHP, and Ruby domains. Also available are domains for Chapel, Common Lisp, dqn, Go, Jinja, Operation, and Scala.