import json

def toJSONFile(obj,filename):
	with open(filename,"w") as f:
		json.dump(obj,f,indent="\t")

def fromJSONFile(filename):
	with open(filename) as f:
		return json.load(f)

class Preferences:
	def __init__(self,filename):
		self.data = fromJSONFile(filename)
		self.filename = filename

	def get(self,id,default=None):
		if id not in self.data.keys():
			return default
		else:
			return self.data[id]

	def set(self,id,val):
		self.data[id] = val
		toJSONFile(self.data,self.filename)