amanuensis/amanuensis/config/dict.py

53 lines
1.3 KiB
Python

"""
Dictionary classes used to represent JSON config files in memory.
"""
from collections import OrderedDict
from amanuensis.errors import ReadOnlyError
class AttrOrderedDict(OrderedDict):
"""
An OrderedDict with attribute access to known keys and explicit
creation of new keys.
"""
def __getattr__(self, key):
if key not in self:
raise AttributeError(key)
return self[key]
def __setattr__(self, key, value):
if key not in self:
raise AttributeError(key)
self[key] = value
def new(self, key, value):
"""Setter for adding new keys"""
if key in self:
raise KeyError("Key already exists: '{}'".format(key))
self[key] = value
class ReadOnlyOrderedDict(OrderedDict):
"""
An OrderedDict that cannot be modified with attribute access to
known keys.
"""
def __readonly__(self, *args, **kwargs):
raise ReadOnlyError("Cannot modify a ReadOnlyOrderedDict")
def __init__(self, *args, **kwargs):
super(ReadOnlyOrderedDict, self).__init__(*args, **kwargs)
self.__setitem__ = self.__readonly__
self.__delitem__ = self.__readonly__
self.pop = self.__readonly__
self.popitem = self.__readonly__
self.clear = self.__readonly__
self.update = self.__readonly__
self.setdefault = self.__readonly__
def __getattr__(self, key):
if key not in self:
raise AttributeError(key)
return self[key]