title: In what situation, is there a need for more than one application in flask ? (not blueprint)
body: <p>A lot of complexity in the flask code base is due to the fact that more than one app can be created. While I grasp the architecture to allow this, I don't quite get, is <strong>when</strong> does it happen ? Or <strong>Why</strong> one does need it ? </p>
  
  <p>To be clear, I am <strong>not</strong> talking about blueprints. I am talking about something like : </p>
  
  <pre><code>from flask import Flask, Blueprint
  
  bp = Blueprint('common', __name__)
  
  @bp.route('/')
  def index():
      return 'Hello World!'
  
  def make_app(filename):
      app = Flask(__name__)
      app.config.from_pyfile(filename)
      app.register_blueprint(bp)
      return app
  
  app1 = make_app('config1.py')
  app2 = make_app('config2.py')
  </code></pre>