Plugin to change previous/next post to reflect section indices instead of global index

v7/section_prevnext/README.md

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+This plugin changes the previous/next links below the posts to reflect the section index instead of the global index.
+This way, the sections of a blog behave more like independent subblogs.
+
+There is no configuration needed, but i recommend to replace the blog index by a static page to avoid confusing readers.
+This can be archived by setting INDEX\_PATH to some subdirectory, adding pages output to the root directory
+
+    PAGES = (
+      ("pages/*.md", "", "story.tmpl"),
+   	)
+
+and creating a corresponding pages/index.md file.
+
+Depends on taxonomies introduced in Nikola 7.8.2 so be sure to use a recent version.

v7/section_prevnext/section_prevnext.plugin

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+[Core]
+name = section_prevnext
+module = section_prevnext
+
+[Documentation]
+author = Alexander Krimm
+version = 0.1
+website = https://plugins.getnikola.com/#section_prevnext
+description = Sets next/previous link according to section index instead of global timeline
+
+[Nikola]
+PluginCategory = SignalHandler
+MinVersion = 7.8.2

v7/section_prevnext/section_prevnext.py

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+# -*- coding: utf-8 -*-
+
+# Copyright © 2017 Alexander Krimm.
+
+# Permission is hereby granted, free of charge, to any
+# person obtaining a copy of this software and associated
+# documentation files (the "Software"), to deal in the
+# Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the
+# Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice
+# shall be included in all copies or substantial portions of
+# the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""Change navigation links below posts to next/previous post in section"""
+
+from __future__ import unicode_literals
+import blinker
+
+from nikola.plugin_categories import SignalHandler
+
+
+class SectionNav(SignalHandler):
+    """Change navigation links below posts to next/previous post in section"""
+
+    name = "section_prevnext"
+
+    def _set_navlinks(self, site):
+        # Needed to avoid strange errors during tests
+        if site is not self.site:
+            return
+        # Update prev_post and next_post
+        for lang, langposts in site.posts_per_classification['section_index'].items():
+            for section, sectionposts in langposts.items():
+                for i, p in enumerate(sectionposts[1:]):
+                    p.next_post = sectionposts[i]
+                for i, p in enumerate(sectionposts[:-1]):
+                    p.prev_post = sectionposts[i + 1]
+                sectionposts[0].next_post = None
+                sectionposts[-1].prev_post = None
+
+    def set_site(self, site):
+        """Set site, which is a Nikola instance."""
+        super(SectionNav, self).set_site(site)
+        # Add hook for after taxonomies_classifier has set site.posts_per_classification
+        blinker.signal("taxonomies_classified").connect(self._set_navlinks)