title: prevent deep copy on python
body: <p>The problem is the following : suppose you have a class 'P' (defined on python), containing some parameters, you want to pass through your main code to differents objects on your code.</p>
  <p>It there any way, to prevent that your instance p of class P, created on the main class, is 'deep copied' throught the code ? ( and ideally, that no other module can instantiate an element of class P, for exemple by forcing at most on instance of the class, is there a short way to do that on python?).</p>
  <p>The aim is to change dynamically, the parameters of of instance P, on the main code (only), and transfer the modification to the whole code with no additionnal manual setting.</p>