[python-debian/jsw/apt-pkg-without-shared-storage] Implement Deb822Dict.__contains__

[John Wright]

By using the internal __dict object's __contains__ method, rather than
making DictMixin look through all the elements of the __keys list, we
significantly speed up operations that require looking to see if the
Deb822Dict already has a particular key (such as __setitem__).  This, in
turn, speeds up the operation of Deb822.iter_paragraphs with
shared_storage=False, so that, except for raw Deb822 paragraphs, the
speed gained by using shared_storage=True is marginal.

So, I also set the default shared_storage parameter for
Deb822.iter_paragraphs to False.  This results in reasonably fast
parsing most of the time, and has less potential for confusion than with
shared_storage=True.
---
 debian_bundle/deb822.py |   20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/debian_bundle/deb822.py b/debian_bundle/deb822.py
index 4527ac7..2ad9115 100644
--- a/debian_bundle/deb822.py
+++ b/debian_bundle/deb822.py
@@ -102,6 +102,9 @@ class Deb822Dict(object, UserDict.DictMixin):
                 return self.__parsed[key]
             else:
                 raise
+
+    def __contains__(self, key):
+        return key in self.__dict
     
     def __delitem__(self, key):
         key = _strI(key)
@@ -168,7 +171,7 @@ class Deb822(Deb822Dict):
         self.gpg_info = None
 
     def iter_paragraphs(cls, sequence, fields=None, use_apt_pkg=True,
-                        shared_storage=True):
+                        shared_storage=False):
         """Generator that yields a Deb822 object for each paragraph in sequence.
 
         :param sequence: same as in __init__.
@@ -178,12 +181,15 @@ class Deb822(Deb822Dict):
         :param use_apt_pkg: if sequence is a file(), apt_pkg will be used 
             if available to parse the file, since it's much much faster.  Set
             this parameter to False to disable using apt_pkg.
-        :param shared_storage: if sequence is a file() and use_apt_pkg is True,
-            yielded objects will share storage, so they can't be kept across
-            iterations. (Also, PGP signatures won't be stripped.) Set this
-            parameter to False to make a copy of the parsed data through each
-            iteration.  This parameter has no effect if use_apt_pkg is False or
-            apt_pkg is not available.
+        :param shared_storage: if sequence is a file(), use_apt_pkg is True,
+            and shared_storage is True, yielded objects will share storage, so
+            they can't be kept across iterations.  (Also, PGP signatures won't
+            be stripped.)  By default, this parameter is False, causing a copy
+            of the parsed data to be made through each iteration.  Except for
+            with raw Deb822 paragraphs (as opposed to _multivalued subclasses),
+            the speed gained by setting shared_storage=True is marginal.  This
+            parameter has no effect if use_apt_pkg is False or apt_pkg is not
+            available.
         """
 
         if _have_apt_pkg and use_apt_pkg and isinstance(sequence, file):
-- 
1.5.5.GIT