Don't spcify unlimited feed size by default

Having a feed with hundreds of articles, making a very large file, is
rarely expected.

Set a high fallback value of 100 so it does not change for small sites.

Still allow to have infinite feed by setting FEED_MAX_ITEM = False

docs/settings.rst

@@ -1000,8 +1000,8 @@ the ``TAG_FEED_ATOM`` and ``TAG_FEED_RSS`` settings:
 
 .. data:: FEED_MAX_ITEMS
 
-   Maximum number of items allowed in a feed. Feed item quantity is
-   unrestricted by default.
+   Maximum number of items allowed in a feed. `False` for unrestricted. 100 if
+   not specified.
 
 .. data:: RSS_FEED_SUMMARY_ONLY = True
 

pelican/writers.py

@@ -143,11 +143,15 @@ def write_feed(self, elements, context, path=None, url=None,
 
         feed = self._create_new_feed(feed_type, feed_title, context)
 
-        max_items = len(elements)
         if self.settings['FEED_MAX_ITEMS']:
-            max_items = min(self.settings['FEED_MAX_ITEMS'], max_items)
-        for i in range(max_items):
-            self._add_item_to_the_feed(feed, elements[i])
+            last_item = self.settings['FEED_MAX_ITEMS']
+        elif isinstance(self.settings['FEED_MAX_ITEMS'], bool):
+            # explicitly set FEED_MAX_ITEMS = False
+            last_item = len(elements)
+        else:
+            last_item = 100
+        for element in elements[:last_item]:
+            self._add_item_to_the_feed(feed, element)
 
         signals.feed_generated.send(context, feed=feed)
         if path: