Examples and templates

Documenting functions

We use the Sphinx directives .. module:: and .. function:: to describe functions of Tarantool modules:

..  module:: fiber

..  function:: create(function [, function-arguments])

    Create and start a fiber. The fiber is created and begins to run immediately.

    :param function: the function to be associated with the fiber
    :param function-arguments: what will be passed to function.
                               If the arguments are optional, put them in
                               square brackets in the function declaration.

    :return: created fiber object
    :rtype: userdata

    **Example:**

    ..  code-block:: tarantoolsession

        tarantool> fiber = require('fiber')
        ---
        ...
        tarantool> function function_name()
                 >   print("I'm a fiber")
                 > end
        ---
        ...
        tarantool> fiber_object = fiber.create(function_name); print("Fiber started")
        I'm a fiber
        Fiber started
        ---
        ...

The resulting output looks like this:

fiber.create(function[, function-arguments])¶

Create and start a fiber. The fiber is created and begins to run immediately.

Parameters:	function – the function to be associated with the fiber function-arguments – what will be passed to function. If the arguments are optional, put them in square brackets in the function declaration.
Return:	created fiber object
Rtype:	userdata

Example:

tarantool> fiber = require('fiber')
---
...
tarantool> function function_name()
         >   print("I'm a fiber")
         > end
---
...
tarantool> fiber_object = fiber.create(function_name); print("Fiber started")
I'm a fiber
Fiber started
---
...

Documenting class methods and data

Methods are described similarly to functions, but the .. class:: directive, unlike .. module::, requires nesting.

As for data, it’s enough to write the description, the return type, and an example.

Here is the example documentation describing the method and data of the index_object class:

..  class:: index_object

    ..  method:: get(key)

        Search for a tuple :ref:`via the given index <box_index-note>`.

        :param index_object index_object: :ref:`object reference
                                          <app_server-object_reference>`
        :param scalar/table      key: values to be matched against the index key

        :return: the tuple whose index-key fields are equal to the passed key values
        :rtype:  tuple

        **Possible errors:**

        * No such index
        * Wrong type
        * More than one tuple matches

        **Complexity factors:** index size, index type.
        See also :ref:`space_object:get() <box_space-get>`.

        **Example:**

        ..  code-block:: tarantoolsession

            tarantool> box.space.tester.index.primary:get(2)
            ---
            - [2, 'Music']
            ...

    ..  data:: unique

        True if the index is unique, false if the index is not unique.

        :rtype: boolean

        ..  code-block:: tarantoolsession

            tarantool> box.space.tester.index.primary.unique
            ---
            - true
            ...

And the resulting output looks like this:

object index_object¶

index_object:get(key)¶

Search for a tuple via the given index.

Parameters:	index_object (index_object) – object reference key (scalar/table) – values to be matched against the index key
Return:	the tuple whose index-key fields are equal to the passed key values
Rtype:	tuple

Possible errors:

• No such index
• Wrong type
• More than one tuple matches

Complexity factors: index size, index type. See also space_object:get().

Example:

tarantool> box.space.tester.index.primary:get(2)
---
- [2, 'Music']
...

index_object.unique¶

True if the index is unique, false if the index is not unique.

Rtype:	boolean

tarantool> box.space.tester.index.primary.unique
---
- true
...

Parameters in functions and classes

This section explains how to document specific function or class method parameters as described above. To learn how to document configuration parameters passed to Tarantool via the command line or in an initialization file, see the next section.

For every function or class method parameter, list the following details:

• General description
• Type
• Default value (if optional), possible values

In the “Possible errors” section of the function or class method, consider explaining what happens if the parameter hasn’t been defined or has the wrong value.

Configuration parameters

For every configuration parameter, list the following details:

• Since which Tarantool version
• General description
• Type
• Corresponding environment variable (if applicable)
• Default value
• Possible values
• Dynamic (yes or no)

..  confval:: wal_dir

    Since version 1.6.2.
    A directory where write-ahead log (``.xlog``) files are stored.
    Can be relative to :ref:`work_dir <cfg_basic-work_dir>`.
    Sometimes ``wal_dir`` and :ref:`memtx_dir <cfg_basic-memtx_dir>` are specified with different values,
    so that write-ahead log files and snapshot files can be stored on different disks.
    If not specified, defaults to ``work_dir``.

    | Type: string
    | Default: "."
    | Environment variable: TT_WAL_DIR
    | Dynamic: no