From 5b22a690cc3d01564b8c8d83a7aa091ade49aa26 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 1 Nov 2014 22:20:29 +0530
Subject: [PATCH] Make render_composite() an internal API

---
 src/calibre/db/cache.py  |  2 +-
 src/calibre/db/fields.py | 13 +++++++++----
 src/calibre/db/lazy.py   |  2 +-
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index b64df49a86..5a48322bd7 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -405,7 +405,7 @@ class Cache(object):
         if mi is None:
             return f.get_value_with_cache(book_id, self._get_proxy_metadata)
         else:
-            return f.render_composite_with_cache(book_id, mi, mi.formatter, mi.template_cache)
+            return f._render_composite_with_cache(book_id, mi, mi.formatter, mi.template_cache)
 
     @read_api
     def field_ids_for(self, name, book_id):
diff --git a/src/calibre/db/fields.py b/src/calibre/db/fields.py
index 3b34670442..adf482808d 100644
--- a/src/calibre/db/fields.py
+++ b/src/calibre/db/fields.py
@@ -253,7 +253,8 @@ class CompositeField(OneToOneField):
     def bool_sort_key(self, val):
         return self._bool_sort_key(force_to_bool(val))
 
-    def render_composite(self, book_id, mi, formatter, template_cache):
+    def __render_composite(self, book_id, mi, formatter, template_cache):
+        ' INTERNAL USE ONLY. DO NOT USE THIS OUTSIDE THIS CLASS! '
         ans = formatter.safe_format(
             self.metadata['display']['composite_template'], mi, _('TEMPLATE ERROR'),
             mi, column_name=self._composite_name, template_cache=template_cache).strip()
@@ -261,11 +262,15 @@ class CompositeField(OneToOneField):
             self._render_cache[book_id] = ans
         return ans
 
-    def render_composite_with_cache(self, book_id, mi, formatter, template_cache):
+    def _render_composite_with_cache(self, book_id, mi, formatter, template_cache):
+        ''' INTERNAL USE ONLY. DO NOT USE METHOD DIRECTLY. INSTEAD USE
+         db.composite_for() OR mi.get(). Those methods make sure there is no
+         risk of infinite recursion when evaluating temoplates that refer to
+         themselves. '''
         with self._lock:
             ans = self._render_cache.get(book_id, None)
         if ans is None:
-            return self.render_composite(book_id, mi, formatter, template_cache)
+            return self.__render_composite(book_id, mi, formatter, template_cache)
         return ans
 
     def clear_caches(self, book_ids=None):
@@ -281,7 +286,7 @@ class CompositeField(OneToOneField):
             ans = self._render_cache.get(book_id, None)
         if ans is None:
             mi = get_metadata(book_id)
-            return self.render_composite(book_id, mi, mi.formatter, mi.template_cache)
+            return self.__render_composite(book_id, mi, mi.formatter, mi.template_cache)
         return ans
 
     def sort_keys_for_books(self, get_metadata, lang_map):
diff --git a/src/calibre/db/lazy.py b/src/calibre/db/lazy.py
index 059ee18762..93a814be1e 100644
--- a/src/calibre/db/lazy.py
+++ b/src/calibre/db/lazy.py
@@ -232,7 +232,7 @@ def composite_getter(mi, field, dbref, book_id, cache, formatter, template_cache
                 except KeyError:
                     ret = cache[field] = _('Invalid field: %s') % field
                 else:
-                    ret = cache[field] = fo.render_composite_with_cache(book_id, mi, formatter, template_cache)
+                    ret = cache[field] = fo._render_composite_with_cache(book_id, mi, formatter, template_cache)
         except Exception:
             import traceback
             traceback.print_exc()