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authorW. Trevor King <wking@drexel.edu>2010-01-22 13:28:01 -0500
committerW. Trevor King <wking@drexel.edu>2010-01-22 13:28:01 -0500
commitd72430fee347e21a9b9e7912417615bbdb22e6d4 (patch)
treef7c5c1db45f38774fdd56322c7e2d3af12c0edcc
parentbda68bb5d93f4b608fb1dd17c5a0cf1bb406daf9 (diff)
downloadbugseverywhere-d72430fee347e21a9b9e7912417615bbdb22e6d4.tar.gz
Added _EMPTY and Storage.exists() to libbe.storage.base.
There seem to be problems distinguishing between "added but unset" IDs and "added and set to ''" IDs. Now _EMPTY lets us mark "added but unset", and Storage.exists() handles "already added?" more clearly than the old hack "does .get() succeed?".
-rw-r--r--libbe/storage/base.py55
1 files changed, 43 insertions, 12 deletions
diff --git a/libbe/storage/base.py b/libbe/storage/base.py
index 202305b..64ae3e7 100644
--- a/libbe/storage/base.py
+++ b/libbe/storage/base.py
@@ -84,9 +84,12 @@ class EmptyCommit(Exception):
def __init__(self):
Exception.__init__(self, 'No changes to commit')
+class _EMPTY (object):
+ """Entry has been added but has no user-set value."""
+ pass
class Entry (Tree):
- def __init__(self, id, value=None, parent=None, directory=False,
+ def __init__(self, id, value=_EMPTY, parent=None, directory=False,
children=None):
if children == None:
Tree.__init__(self)
@@ -241,10 +244,7 @@ class Storage (object):
"""Add an entry"""
if self.is_writeable() == False:
raise NotWriteable('Cannot add entry to unwriteable storage.')
- try: # Maybe we've already added that id?
- self.get(id)
- pass # yup, no need to add another
- except InvalidID:
+ if not self.exists(id):
self._add(id, *args, **kwargs)
def _add(self, id, parent=None, directory=False):
@@ -253,6 +253,15 @@ class Storage (object):
p = self._data[parent]
self._data[id] = Entry(id, parent=p, directory=directory)
+ def exists(self, *args, **kwargs):
+ """Check an entry's existence"""
+ if self.is_readable() == False:
+ raise NotReadable('Cannot check entry existence in unreadable storage.')
+ return self._exists(*args, **kwargs)
+
+ def _exists(self, id, revision=None):
+ return id in self._data
+
def remove(self, *args, **kwargs):
"""Remove an entry."""
if self.is_writeable() == False:
@@ -332,7 +341,7 @@ class Storage (object):
return value
def _get(self, id, default=InvalidObject, revision=None):
- if id in self._data:
+ if id in self._data and self._data[id].value != _EMPTY:
return self._data[id].value
elif default == InvalidObject:
raise InvalidID(id)
@@ -402,6 +411,13 @@ class VersionedStorage (Storage):
p = self._data[-1][parent]
self._data[-1][id] = Entry(id, parent=p, directory=directory)
+ def _exists(self, id, revision=None):
+ if revision == None:
+ revision = -1
+ else:
+ revision = int(revision)
+ return id in self._data[revision]
+
def _remove(self, id):
if self._data[-1][id].directory == True \
and len(self.children(id)) > 0:
@@ -446,7 +462,8 @@ class VersionedStorage (Storage):
revision = -1
else:
revision = int(revision)
- if id in self._data[revision]:
+ if id in self._data[revision] \
+ and self._data[revision][id].value != _EMPTY:
return self._data[revision][id].value
elif default == InvalidObject:
raise InvalidID(id)
@@ -760,13 +777,14 @@ if TESTING == True:
pass
def test_get_initial_value(self):
- """Data value should be None before any value has been set.
+ """Data value should be default before any value has been set.
"""
self.s.add(self.id, directory=False)
- ret = self.s.get(self.id)
- self.failUnless(ret == None,
- "%s.get() returned %s not None"
- % (vars(self.Class)['name'], ret))
+ val = 'UNLIKELY DEFAULT'
+ ret = self.s.get(self.id, default=val)
+ self.failUnless(ret == val,
+ "%s.get() returned %s not %s"
+ % (vars(self.Class)['name'], ret, val))
def test_set_exception(self):
"""Set should raise exception if id not in Storage.
@@ -830,6 +848,19 @@ if TESTING == True:
"%s.get() returned %s not %s"
% (vars(self.Class)['name'], ret, self.val))
+ def test_empty_get_set_persistence(self):
+ """After empty set, get may return either an empty string or default.
+ """
+ self.s.add(self.id, directory=False)
+ self.s.set(self.id, '')
+ self.s.disconnect()
+ self.s.connect()
+ default = 'UNLIKELY DEFAULT'
+ ret = self.s.get(self.id, default=default)
+ self.failUnless(ret in ['', default],
+ "%s.get() returned %s not in %s"
+ % (vars(self.Class)['name'], ret, ['', default]))
+
def test_add_nonrooted_persistence(self):
"""Adding entries should increase the number of children after reconnect.
"""