Make _DictManager private. (#858)

* Make _DictManager private.

* Update changelog.

changelog.txt

@@ -60,6 +60,7 @@ Removed
  - The public API of the ``synced_collection`` subpackage (#807, #790).
  - The warnings module (#815).
  - The signac.common.validate module (#853).
+ - The ``DictManager`` class (#858).
 
 Version 1
 =========

signac/core/dict_manager.py

@@ -11,8 +11,7 @@
 from .utility import _safe_relpath
 
 
-# TODO: Make this private. This shouldn't be part of our API.
-class DictManager:
+class _DictManager:
     """Helper class to manage multiple instances of dict-like classes.
 
     This class is designed to manage multiple dict-like interface classes to files
@@ -32,10 +31,10 @@ class DictManager:
     def __init__(self, prefix):
         assert (
             self.cls is not None
-        ), "Subclasses of DictManager must define the cls variable."
+        ), "Subclasses of _DictManager must define the cls variable."
         assert (
             self.suffix is not None
-        ), "Subclasses of DictManager must define the suffix variable."
+        ), "Subclasses of _DictManager must define the suffix variable."
         self._prefix = os.path.abspath(prefix)
         self._dict_registry = {}
 

signac/core/h5store.py

@@ -11,7 +11,7 @@
 from threading import RLock
 
 from ..errors import H5StoreAlreadyOpenError, H5StoreClosedError, InvalidKeyError
-from .dict_manager import DictManager
+from .dict_manager import _DictManager
 from .utility import _safe_relpath
 
 __all__ = [
@@ -523,7 +523,7 @@ def clear(self):
             self._file.clear()
 
 
-class H5StoreManager(DictManager):
+class H5StoreManager(_DictManager):
     """Helper class to manage multiple instances of :class:`~.H5Store` within a directory.
 
     Parameters