# Epydoc Fields

Fields are used to describe specific properties of a documented object. For example, fields can be used to define the parameters and return value of a function; the instance variables of a class; and the author of a module. Each field consists of a tag, an optional argument, and a body.

- The tag is a case-insensitive word that indicates what kind of documentation is given by the field.
- The optional argument specifies what object, parameter, or group is documented by the field.
- The body contains the main contents of the field.

# Field Markup

Each docstring markup langauge marks fields differently. The following table shows the basic fields syntax for each markup language. For more information, see the definition of field syntax for each markup language.

Epytext | reStructuredText | Javadoc
--- | --- | ---
    @tag: body...
    @tag arg: body...
    :tag: body...
    :tag arg: body...
    @tag body...
    @tag arg body...
Definition of epytext fields | Definition of ReStructuredText fields | Definition of Javadoc fields

# Supported Fields

The following table lists the fields that epydoc currently recognizes. Field tags are written using epytext markup; if you are using a different markup language, then you should adjust the markup accordingly.

## Functions and Methods parameters

`@param` p: ...
  A description of the parameter p for a function or method.
`@type` p: ...
  The expected type for the parameter p.
`@return`: ...
  The return value for a function or method.
`@rtype`: ...
  The type of the return value for a function or method.
`@keyword` p: ...
  A description of the keyword parameter p.
`@raise` e: ...
  A description of the circumstances under which a function or method raises exception e.

These tags can be used to specify attributes of parameters and return value of function and methods. These tags are usually put in the the docstring of the function to be documented.

Note

constructor parameters

In C extension modules, extension classes cannot have a docstring attached to the `__init__` function; consequently it is not possible to document parameters and exceptions raised by the class constructor. To overcome this shortcoming, the tags `@param`, `@keyword`, `@type`, `@exception` are also allowed to appear in the class docstring. In this case they refer to constructor parameters.

`@param` fields should be used to document any explicit parameter (including the keyword parameter). `@keyword` fields should only be used for non-explicit keyword parameters:

    def plant(seed, *tools, **options):
        """
        @param seed: The seed that should be planted.
        @param tools: Tools that should be used to plant the seed.
        @param options: Any extra options for the planting.

        @keyword dig_deep: Plant the seed deep under ground.
        @keyword soak: Soak the seed before planting it.
        """
        #[...]

Since the `@type` field allows for arbitrary text, it does not automatically create a crossreference link to the specified type, and is not written in fixed-width font by default. If you want to create a crossreference link to the type, or to write the type in a fixed-width font, then you must use inline markup:

    def ponder(person, time):
        """
        @param person: Who should think.
        @type person: L{Person} or L{Animal}
        @param time: How long they should think.
        @type time: C{int} or C{float}
        """
        #[...]

## Variables parameters

`@ivar` v: ...
  A description of the class instance variable v.
`@cvar` v: ...
  A description of the static class variable v.
`@var` v: ...
  A description of the module variable v.
`@type` v: ...
  The type of the variable v.

These tags are usually put in a module or class docstring. If the sources can be parsed by Epydoc it is also possible to document the variable in their own docstrings: see variable docstrings

Epydoc considers class variables the ones defined directly defined in the class body. A common Python idiom is to create instance variables settings their default value in the class instead of the constructor (hopefully if the default is immutable...).

If you want to force Epydoc to classify as instance variable one whose default value is set at class level, you can describe it using the tag `@ivar` in the context of a variable docstring:

    class B:
        y = 42
        """@ivar: This is an instance variable."""

## Properties parameters

`@type`: ...
  The type of the property.

The `@type` tag can be attached toa property docstring to specify its type.

## Grouping and Sorting

`@group` g: c1,...,cn
  Organizes a set of related children of a module or class into a group. g is the name of the group; and c1,...,cn are the names of the children in the group. To define multiple groups, use multiple group fields.
`@sort`: c1,...,cn
  Specifies the sort order for the children of a module or class. c1,...,cn are the names of the children, in the order in which they should appear. Any children that are not included in this list will appear after the children from this list, in alphabetical order.

These tags can be used to present groups of related items in a logical way. They apply to modules and classes docstrings.

For the `@group` and `@sort` tags, asterisks (`*`) can be used to specify multiple children at once. An asterisk in a child name will match any substring:

    class widget(size, weight, age):
        """
        @group Tools: zip, zap, *_tool
        @group Accessors: get_*
        @sort: get_*, set_*, unpack_*, cut
        """
        #[...]

Note

group markers

It is also possible to group set of related items enclosing them into special comment starting with the group markers '`#{`' and '`#}`' The group title can be specified after the opening group marker. Example:

    #{ Database access functions

    def read(id):
        #[...]

    def store(item):
        #[...]

    def delete(id):
        #[...]

    # groups can't be nested, so a closing marker is not required here.

    #{ Web publish functions

    def get(request):
        #[...]

    def post(request):
        #[...]

    #}

## Notes and Warnings

`@note`: ...
  A note about an object. Multiple note fields may be used to list separate notes.
`@attention`: ...
  An important note about an object. Multiple attention fields may be used to list separate notes.
`@bug`: ...

  A description of a bug in an object. Multiple bug fields may be used to report separate bugs.

  Note

  If any `@bug` field is used, the HTML writer will generate a the page `bug-index.html`, containing links to all the items tagged with the field.

`@warning`: ...
  A warning about an object. Multiple warning fields may be used to report separate warnings.

## Status

`@version`: ...
  The current version of an object.
`@todo` [ver]: ...

  A planned change to an object. If the optional argument ver is given, then it specifies the version for which the change will be made. Multiple todo fields may be used if multiple changes are planned.

  Note

  If any `@todo` field is used, the HTML writer will generate a the page `todo-index.html`, containing links to all the items tagged with the field.

`@deprecated`: ...
  Indicates that an object is deprecated. The body of the field describe the reason why the object is deprecated.
`@since`: ...
  The date or version when an object was first introduced.
`@status`: ...
  The current status of an object.
`@change`: ...
  A change log entry for this object.
`@permission`: ...
  The object access permission, for systems such Zope/Plone supporting this concept. It may be used more than once to specify multiple permissions.

## Formal Conditions

`@requires`: ...
  A requirement for using an object. Multiple requires fields may be used if an object has multiple requirements.
`@precondition`: ...
  A condition that must be true before an object is used. Multiple precondition fields may be used if an object has multiple preconditions.
`@postcondition`: ...
  A condition that is guaranteed to be true after an object is used. Multiple postcondition fields may be used if an object has multiple postconditions.
`@invariant`: ...
  A condition which should always be true for an object. Multiple invariant fields may be used if an object has multiple invariants.

## Bibliographic Information

`@author`: ...
  The author(s) of an object. Multiple author fields may be used if an object has multiple authors.
`@organization`: ...
  The organization that created or maintains an object.
`@copyright`: ...
  The copyright information for an object.
`@license`: ...
  The licensing information for an object.
`@contact`: ...
  Contact information for the author or maintainer of a module, class, function, or method. Multiple contact fields may be used if an object has multiple contacts.

## Other fields

`@summary`: ...
  A summary description for an object. This description overrides the default summary (which is constructed from the first sentence of the object's description).
`@see`: ...
  A description of a related topic. see fields typically use documentation crossreference links or external hyperlinks that link to the related topic.

# Fields synonyms

Several fields have synonyms, or alternate tags. The following table lists all field synonyms. Field tags are written using epytext markup; if you are using a different markup language, then you should adjust the markup accordingly.

Name | Synonims
--- | ---
`@param` p: ... | `@parameter` p: ... `@arg` p: ... `@argument` p: ...
`@return`: ... | `@returns`: ...
`@rtype`: ... | `@returntype`: ...
`@raise` e: ... | `@raises` e: ... `@except` e: ... `@exception` e: ...
`@keyword` p: ... | `@kwarg` p: ... `@kwparam` p: ...
`@ivar` v: ... | `@ivariable` v: ...
`@cvar` v: ... | `@cvariable` v: ...
`@var` v: ... | `@variable` v: ...
`@see`: ... | `@seealso`: ...
`@warning`: ... | `@warn`: ...
`@requires`: ... | `@require`: ... `@requirement`: ...
`@precondition`: ... | `@precond`: ...
`@postcondition`: ... | `@postcond`: ...
`@organization`: ... | `@org`: ...
`@copyright`: ... | `@(c)`: ...
`@change`: ... | `@changed`: ...

# Module metadata variables

Some module variables are commonly used as module metadata. Epydoc can use the value provided by these variables as alternate form for tags. The following table lists the recognized variables and the tag they replace. Customized metadata variables can be added using the method described in Adding New Fields.

Tag | Variable
--- | ---
`@author` | `__author__`
`@authors` | `__authors__`
`@contact` | `__contact__`
`@copyright` | `__copyright__`
`@license` | `__license__`
`@deprecated` | `__deprecated__`
`@date` | `__date__`
`@version` | `__version__`

# Adding New Fields

New fields can be defined for the docstrings in a module using the special `@newfield` tag (or its synonym, `@deffield`). This tag has the following syntax:

>     @newfield tag: label [, plural ]

Where tag is the new tag that's being defined; label is a string that will be used to mark this field in the generated output; and plural is the plural form of label, if different.

New fields can be defined in any Python module. If they are defined in a package, it will be possible to use the newly defined tag from every package submodule.

Each new field will also define a metadata variable which can be used to set the field value instead of the tag. For example, if a revision tag has been defined with:

    @newfield revision: Revision

then it will be possible to set a value for the field using a module variable:

    __revision__ = "1234"

The following example illustrates how the @newfield can be used: Docstring Input Rendered Output

Docstring Input | Rendered Output
--- | ---
    """
    @newfield corpus: Corpus, Corpora
    """

    def example():
        """
        @corpus: Bob's wordlist.
        @corpus: The British National Corpus.
        """
        [...]
| Corpora: Bob's wordlist. The British National Corpus.

Note

The module-level variable `__extra_epydoc_fields__` is deprecated; use `@newfield` instead.