add small extension to get the edit on github button working

Author: lheagy

_ext/edit_on_github.py

@@ -0,0 +1,42 @@
+"""
+Sphinx extension to add ReadTheDocs-style "Edit on GitHub" links to the
+sidebar.
+
+Loosely based on https://github.com/astropy/astropy/pull/347
+"""
+
+import os
+import warnings
+
+
+__licence__ = 'BSD (3 clause)'
+
+
+def get_github_url(app, view, path):
+    return 'https://github.com/{project}/{view}/{branch}/{path}'.format(
+        project=app.config.edit_on_github_project,
+        view=view,
+        branch=app.config.edit_on_github_branch,
+        path=path)
+
+
+def html_page_context(app, pagename, templatename, context, doctree):
+    if templatename != 'page.html':
+        return
+
+    if not app.config.edit_on_github_project:
+        warnings.warn("edit_on_github_project not specified")
+        return
+
+    path = os.path.relpath(doctree.get('source'), app.builder.srcdir)
+    show_url = get_github_url(app, 'blob', path)
+    edit_url = get_github_url(app, 'edit', path)
+
+    # context['show_on_github_url'] = show_url
+    context['edit_on_github_url'] = edit_url
+
+
+def setup(app):
+    app.add_config_value('edit_on_github_project', '', True)
+    app.add_config_value('edit_on_github_branch', 'master', True)
+    app.connect('html-page-context', html_page_context)

conf.py

@@ -41,6 +41,7 @@
     'sphinxcontrib.bibtex',
     'sphinx_rtd_theme',
     'matplotlib.sphinxext.plot_directive',
+    'edit_on_github',
     'purpose',
     'question',
     'geosciapp',
@@ -83,7 +84,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used:
@@ -156,6 +157,11 @@
 # number figures
 numfig = True
 
+# -- Edit on Github Extension ---------------------------------------------
+
+edit_on_github_project = 'geoscixyz/em'
+edit_on_github_branch = 'main'
+
 
 # -- Options for HTML output ----------------------------------------------
 
@@ -164,13 +170,13 @@
 
 import sphinx_rtd_theme
 html_theme = 'sphinx_rtd_theme'
-html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-html_context = {
-  'display_github': True,
-  'github_user': 'geoscixyz',
-  'github_repo': 'em',
-  'github_version': 'main'
-}
+# html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+# html_context = {
+#   'display_github': True,
+#   'github_user': 'geoscixyz',
+#   'github_repo': 'em',
+#   'github_version': 'main'
+# }
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
 html_title = 'Electromagnetic Geophysics'