.. This file is part of Sympathy for Data.
.. Copyright (c) 2010-2019 Combine Control Systems AB
..
.. Sympathy for Data is free software: you can redistribute it and/or modify
.. it under the terms of the GNU General Public License as published by
.. the Free Software Foundation, version 3 of the License.
..
.. Sympathy for Data is distributed in the hope that it will be useful,
.. but WITHOUT ANY WARRANTY; without even the implied warranty of
.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.. GNU General Public License for more details.
..
.. You should have received a copy of the GNU General Public License
.. along with Sympathy for Data.  If not, see <http://www.gnu.org/licenses/>.

.. _`libraries`:

Libraries
=========

.. _`library_wizard`:

Creating new libraries
----------------------
When Sympathy starts it looks for nodes in all library folders, seen in
:ref:`Node Libraries Preferences<preferences_node_libraries>` and to create
your own node or plugins, first you have to create a library and add it to
Sympathy's list of libraries.

To create a library all you need to do is use the Library Wizard.
Start it by clicking *File* -> *Wizards* -> *New Library*.

On the first page you will add some meta data about your library. Only name
and identifier are mandatory, but go ahead and add as much as you can!

On the second page you will select the path where the library will be saved, and
a preview of the folders and files created will be displayed.  You can change
the Package name (symbolizied by <package-name> in the following sections) if
you want, but this is not needed.

When you have finished the wizard, the library has been automatically added to
:ref:`Node Libraries Preferences<preferences_node_libraries>`. Note, this is
not synonymous with adding libraries to the library view.

.. _`new_library`:

New Library Format
------------------

Starting with Sympathy 2.0.0 there is a new format for libraries that is more
"python-like". One benefit from the new format is the ability to distribute
libraries like any other python package. When you are creating a new library
the new format is recommended unless you also need to support older Sympathy
versions.

Library structure
^^^^^^^^^^^^^^^^^

This is the new, recommended way to structure a node library::

  <library-root>
  ├── setup.py
  ├── src
  │   └── <package-name>
  │       ├── __init__.py
  │       ├── flows
  │       │   └── ... (flows)
  │       ├── nodes
  │       │   └── ... (nodes)
  │       └── plugins
  │           └── ... (plugins)
  │       └── examples
  │           └── ... (example flows)
  └── test
      ├── test.py
      ├── flows
      │   └── ... (test flows)
      └── ... (unit tests)


Tests of your library's functionality should be placed in test and Example flows
that show off how your nodes work should be placed in example. Test and examples
folders are completely optional.


Library meta data
^^^^^^^^^^^^^^^^^

Meta data fields are defined as functions without arguments.


.. automodule:: sympathy.api.library
   :members: required_features,
             identifier,
             name,
             icon,
             maintainer,
             copyright,
             version,
             nodes,
             flows,
             plugins,
             examples_path,
             repository_url,
             documentation_url,
             home_url

   .. method:: tags()

      Tags for organizing nodes in Library View.

      Return value and type ommited, see the source for actual values.

   .. method:: types()

      Port type definitions.

      Return value and type ommited, see the source for actual values.


The file __init__.py in the <package-name> can be edited to customize the
meta data for libraries.


.. _`old_library`:

Old Library Format
------------------

.. _`library_structure`:


Older library format used in Sympathy before 2.0.0. Recommended if you want
the library to be usable from older Sympathy versions.


Library structure
^^^^^^^^^^^^^^^^^

This is the old way to structure a node library::

  <Library-root>
  ├─ Library
  │  └─ <Library-name>
  │     └─ ... (nodes & plugins)
  ├─ Common
  │  └─ <package-name>
  │     └─ ... (python modules)
  ├─ Tests
  │  ├─ Unit
  │  │  └─ test.py
  │  └─ Workflow
  │     └─ ... (test flows)
  ├─ Examples
  └─ library.ini

The Library folder is where you put nodes and plugins. The Common folder is for
additional python modules. Tests of your library's functionality should be
placed in Tests and Example flows that show off how your nodes work should be
placed in Examples. Tests and Examples folders are completely optional.


.. _`library_metadata`:

Library meta data
^^^^^^^^^^^^^^^^^

The file Library.ini in the library root may contain extra meta data for the
library. The following fields are recognized in the General section:

``name``
  The human readable name of the library.

``description``
  The human readable description of the library.

``identifier``
  And identifier for this library. Should only contain

``library_path``
  The path of the library folder relative to the library root.

``common_path``
  The path of the package inside the common folder relative to the library root.

``maintainer``
  The name and contact information of the current maintainer of the libary.
  Can be an indiviual person, an organisation or a community.

``copyright``
  A copyright notice that is shown with all nodes.

``repository``
  Url to repository for the library).

``documentation``
  Url to documentation for the library).

``home``
  Url to home for the library).


Add extra modules to your library
---------------------------------
If your node code is starting to become too big to keep it all in a single file
or if you created some nice utility functions that you want to use in several
different node files you can place them in the <package-name> folder.


Open your favorite editor and create the file::

    <package-name>/mymodule.py

The parent of the <package-name> folder will automatically be added to ``sys.path`` so you will
be able to import modules from that package in your node code::

    from <package-name> import mymodule


.. _`library_tags`:

Library tags
------------
Each library may define additional node tags. These tag definitions go into the
file <package_name>/__init__.py, and it can look something like this::

    from sympathy.api.nodeconfig import LibraryTags, TagType, GroupTagType

	# Assuming a new library format.
	# If you use Old Library Format, rename tags() function to library_tags().
    def tags():
        return [
            ExamplelibLibraryTags
        ]


    class ExamplelibLibraryTags(LibraryTags):
        class_tags = (
            GroupTagType(
                'example',

                # First group
                [GroupTagType(
                    'GroupOne',
                    [TagType('TagOne',
                             'Tag description'),
                     TagType('TagTwo',
                             'Tag description')]
                ),

                # Second group
                GroupTagType(
                    'GroupTwo',
                    [TagType('TagOne',
                             'Tag description',
                             name='Optional tag name that can hold non-alphabetic characters')]
                ),

                # Third group
                GroupTagType(
                    'GroupThree',
                    [TagType('TagOne',
                             'Tag description'),
                     TagType('TagTwo',
                             'Tag description'),
                     TagType('TagThree',
                             'Tag description')],
                    name='Optional group name that can hold non-alphabetic characters')
                ]
            )
        )

        def __init__(self):
            super().__init__()
            self._root = self.class_tags

This will create a structure like below (if using Separated Tag Layout,
otherwise the tags will be mixed in with those already existing):

.. figure:: screenshot_example_tags.png
   :alt: Custom tags example
   :align: center

Note that tags won't show up in the tree until they are used by at least one
node. The tags are searchable when using Wizards to create new nodes.


.. _example_flows:

Example flows
-------------
Workflows in the Examples directory (create it, if it does not exist, before
adding example flows) of a library will be treated as examples.

Example flows are treated similarly to test workflows in that they are executed
automatically when running the built-in test suite. See :ref:`lib_tests`.

Additionally, example flows can specify (on the top-level) that they are
examples for one or several nodes by including a reference in the following
format: :code:`Node example: *<node-identifier>*` (for example, :code:`Node
example: *com.example.boblib.helloworld*`) inside text fields.  Alternatively,
to make the example reference fit better as part of a sentence, the following
format is also supported: :code:`Node example for *<node-identifier>*`.

The documentation for referenced nodes will include links to referencing
example flows. Example flows are copied into the documentation folder and as a
rule, it is best if they are self-contained and do not depend on other
workflows or data files.