Is it possible to reuse hyperlink defined in another file in restructuredtext (or sphinx) - python-sphinx

Question

Suppose I have two files a.rst and b.rst in the same folder, and a.rst looks like this
.. _foo: http://stackoverflow.com
`foo`_ is a website
It seems using foo in b.rst is not allowed. Is there a way to define hyperlinks and use them in multiple files?
Followup
I used the extlinks extension as Steve Piercy suggested. Its implementation and docstring can be seen here on github.
In my case, I define wikipedia link in my conf.py
extlinks = {'wiki': ('https://en.wikipedia.org/wiki/%s', '')}
and in the .rst files, use them like
:wiki:`Einstein <Albert_Einstein>`
where Einstein will be displayed as a link to https://en.wikipedia.org/wiki/Albert_Einstein

Answer 1

There are at least four possible solutions.
1. repeat yourself
Put your complete reST in each file. You probably don't want that.
2. combined rst_epilog and substitution
This one is clever. Configure the rst_epilog value, in your conf.py along with a substition with the replace directive:
rst_epilog = """
.. |foo| replace:: foo
.. _foo: http://stackoverflow.com
"""
and reST:
|foo|_ is a website
yields:
<a class="reference external" href="http://stackoverflow.com">foo</a>
3. extlinks
For links to external websites where you want to have a base URL and append path segments or arguments, you can use extlinks in your conf.py:
extensions = [
...
'sphinx.ext.extlinks',
...
]
...
extlinks = {'so': ('https://stackoverflow.com/%s', None)}
Then in your reST:
:so:`questions/49016433`
Yields:
<a class="reference external"
href="https://stackoverflow.com/questions/49016433">
https://stackoverflow.com/questions/49016433
</a>
4. intersphinx
For external websites that are documentation generated by Sphinx, then you can use intersphinx, in your conf.py:
extensions = [
...
'sphinx.ext.intersphinx',
...
]
...
intersphinx_mapping = {
'python': ('https://docs.python.org/3', None),
}
Then in your reST:
:py:mod:`doctest`
Yields:
<a class="reference external"
href="https://docs.python.org/3/library/doctest.html#module-doctest"
title="(in Python v3.6)">
<code class="xref py py-mod docutils literal">
<span class="pre">doctest</span>
</code>
</a>

Answer 2

This might come a bit late but I have found a solution that works very neatly for me and it is not among the answers already given.
In my case, I create a file with all the links used in my project, save it as /include/links.rst, and looking something like:
.. _PEP8: https://www.python.org/dev/peps/pep-0008/
.. _numpydoc: https://numpydoc.readthedocs.io/en/latest/format.html
.. _googledoc: https://google.github.io/styleguide/pyguide.html
Then there are the files a.rst and b.rst looking like:
.. include:: /include/links.rst
File A.rst
##########
Click `here <PEP8_>`_ to see the PEP8 coding style
Alternatively, visit either:
- `Numpy Style <numpydoc_>`_
- `Google Style <googledoc_>`_
and
.. include:: /include/links.rst
File B.rst
##########
You can visit `Python's PEP8 Style Guide <PEP8_>`_
For docstrings, you can use either `Numpy's <numpydoc_>`_ or `Google's <googledoc_>`_
respectively.
The produced output for both cases is:
and
respectively.
Moreover, I would like to emphasize the fact of which I was actually really struggling to achieve, to use different names (displayed text) for the same link at different locations and which I have achieved with the double _, one inside the <..._> and another outside.

Answer 3

This is another solution: it is a bit hacky and a little bit different respect to the officially supported way to share external links.
First complete the Setup then:
in conf.py add the commonlinks entry in extensions
in conf.py configure the map of common links:
For example:
extensions = [
...,
'sphinx.ext.commonlinks'
]
commonlinks = {
'issues': 'https://github.com/sphinx-doc/sphinx/issues',
'github': 'https://github.com'
}
Then in .rst files you can do these:
The :github:`_url_` url is aliased to :github:`GitHub` and also to :github:`this`
Setup
All that is needed is to copy into sphinx/ext directory the file commonlinks.py:
# -*- coding: utf-8 -*-
"""
sphinx.ext.commonlinks
~~~~~~~~~~~~~~~~~~~~~~
Extension to save typing and prevent hard-coding of common URLs in the reST
files.
This adds a new config value called ``commonlinks`` that is created like this::
commonlinks = {'exmpl': 'http://example.com/mypage.html', ...}
Now you can use e.g. :exmpl:`foo` in your documents. This will create a
link to ``http://example.com/mypage.html``. The link caption depends on the
role content:
- If it is ``_url_``, the caption will be the full URL.
- If it is a string, the caption will be the role content.
"""
from six import iteritems
from docutils import nodes, utils
import sphinx
from sphinx.util.nodes import split_explicit_title
def make_link_role(base_url):
def role(typ, rawtext, text, lineno, inliner, options={}, content=[]):
text = utils.unescape(text)
if text == '_url_':
title = base_url
else:
title = text
pnode = nodes.reference(title, title, internal=False, refuri=base_url)
return [pnode], []
return role
def setup_link_roles(app):
for name, base_url in iteritems(app.config.commonlinks):
app.add_role(name, make_link_role(base_url))
def setup(app):
app.add_config_value('commonlinks', {}, 'env')
app.connect('builder-inited', setup_link_roles)
return {'version': sphinx.__display_version__, 'parallel_read_safe': True}
To locate the sphinx installation directory one way is:
$ python 3
> import sphinx
> sphinx
<module 'sphinx' from '/usr/local/lib/python3.5/dist-packages/sphinx/__init__.py'>
then:
% cp commonlinks.py /usr/local/lib/python3.5/dist-packages/sphinx/ext