# 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 documentaiton 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.

## 1. 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

## 2. 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 (function or method docstrings)
`@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`.
Variables (module or class docstrings)
`@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`.
Properties (property docstrings)
`@type:` ... | The type of the property.
Grouping and Sorting (module, class, function, or method docstrings)
`@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.
Related Topics
`@see:` ... | A description of a related topic. `see` fields typically use documentation crossreference links or external hyperlinks that link to the related topic.
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.
`@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.
`@depreciated:` ... | Indicates that an object is depreciated. The body of the field describe the reason why the object is depreciated.
`@since:` ... | The date or version when an object was first introduced.
`@status:` ... | The current status of an object.
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.
`@organiation:` ... | 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.
Summarization
`@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).

### 2.1. Notes on Supported Fields

- `@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.
          """
          [...]

- 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
          """
          [...]

- 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}
          """
          [...]

## 3. Field 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 | Synonyms
--- | ---
`@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:` ...
Name | Synonyms
--- | ---
`@var v:` ... | `@variable v:` ...
`@see:` ... | `@seealso:` ...
`@warning:` ... | `@warn:` ...
`@requires:` ... | `@require:` ... `@requirement:` ...
`@precondition:` ... | `@precond:` ...
`@postcondition:` ... | `@postcod:` ...
`@organization:` ... | `@org:` ...
`@copyright:` ... | `@(c):` ...

## 4. Adding New Fields

New fields can be defined for the docstrings in a module with the special module-level variable "`__extra_epydoc_fields__`". This variable should contain a list of field specifications, where each field specification is one of the following:

- A single string, which defines both the tag and the label for the field.
- A tuple `(tag, label)`, where `tag` is the field's tag, and `label` is its label.
- A tuple `(tag, singular, plural)`, where `tag` is the field's tag, `singular` is the label that is used when the field has one entry, and `plural` is the label that is used when the field has multiple entries.

The following example illustrates how the special variable "`__extra_epydoc_fields__"` can be used:

Docstring Input | Rendered Output
--- | ---
    __extra_epydoc_fields__ = [
        ('corpus', 'Corpus', 'Corpora')]

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

New fields can also be defined for an individual docstring, using the special `@newfield` field. In particular, "`@newfield tag: label [, plural]`" will define a new field, whose tag is `tag`; and which is labeled in output documentation as `label`. The optional argument `plural` specifies the label that should be used if the field has multiple entries.

## 5. Markup-Specific Notes

For the most part, fields are treated identically, regardless of what markup language is used to encode them. However, there are a few minor differences, which are intended to accomodate existing standards for each markup language. In particular:

- ReStructuredText supports an extra group of fields, called consolidated fields, which combine the documentation for several objects into a single field.
- Javadoc uses a special syntax for the body of the `@see` fields.
- Javadoc does not support multi-word arguments.

For more information about these differences, read the subsections below.

### 5.1. ReStructuredText Fields

In ReStructuredText, a single field can be used to encode the documentation for a group of related items. For example, a single `:Parameters:` field is often used to describe all of the parameters for a function or method:

    def fox_speed(size, weight, age):
        """
        Return the maximum speed for a fox.

        :Parameters:
          - `size`: The size of the fox (in meters)
          - `weight`: The weight of the fox (in stones)
          - `age`: The age of the fox (in years)
        """
        [...]

These types of combined fields are called consolidated fields, and epydoc automatically divides them into their constituant basic fields. The following consolidated fields are currently supported by epydoc:

Consolidated Field Tag | Corresponding Base Field Tag
--- | ---
`:Parameters:` | `:param:`
`:Exceptions:` | `:except:`
`:Groups:` | `:group:`
`:Keywords:` | `:keyword:`
Consolidated Field Tag | Corresponding Base Field Tag
--- | ---
`:Variables:` | `:var:`
`:Ivariables:` | `:ivar:`
`:Cvariables:` | `:cvar:`
`:Types:` | `:type:`

Consolidated fields are required to contain a single list, where each list item begins with a paragraph that begins with an interpreted text string (``...``).

### 5.2. Javadoc Fields

For compatibility with Javadoc, every `@see` field is assumed to contain a single crossreference link, unless its body is quoted, or it start with an HTML tag. See the Javadoc reference manual for more information about how the `@see` field is encoded in Javadoc.

Because Javadoc does not mark end of the optional argument, field arguments must contain exactly one word. Thus, multi-word arguments are not available in Javadoc. In particular, all group names must be single words.

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Last modified: Sun Feb 29 00:45:51 EST 2004