EchoBot economy.py

from discord.ext import commands
import json

class Economy(commands.Cog):

    def __init__(self, bot):
        self.bot = bot
        self.users = self.load()

    # e!balance - Check Gold balance
    @commands.command(pass_context=True)
    async def balance(self, ctx):
        """Check your current Gold balance."""
        self.user_register(ctx.message.author)

        await ctx.send("{} You have {} Gold.".format(ctx.message.author.mention, self.user_balance(ctx.message.author)))

    # Economy functions #

    # Returns whether user is already in data dictionary.
    def user_has_data(self, user):
        return user.id in self.users

    # Add user id to dictionary if missing.
    def user_register(self, user):
        if not self.user_has_data(user):
            self.users[user.id] = {'id': user.id, 'name': user.name, 'balance': 100}
            self.save()

    def user_balance(self, user):
        if self.user_has_data(user):
            return self.users[user.id]['balance']
        else:
            return None

    # Data functions #

    # Save all user data to file.
    def save(self):
        file = open('users.json', 'w+')
        json.dump(self.users, file, indent=4)

        file.close()

    # Load user data from file into dictionary.
    def load(self):
        file = open('users.json', 'r')

        data = json.load(file)
        file.close()

        return data

def setup(bot):
    bot.add_cog(Economy(bot))
    print("Loaded economy system.")