#!/usr/bin/env python
# coding: utf-8

# # Updatable displays proposal
# 
# - `display(...display_id=True) generates a new, random display_id
# - `display(...display_id=anything)` returns a `handle` with `.display(obj)` and `.update(obj)` methods.

# In[1]:


from IPython.display import display, update_display


# In[2]:


handle = display('x', display_id=True)
handle


# In[3]:


handle.display('y')


# In[4]:


handle.update('z')


# In[5]:


display('x', display_id='here');


# In[6]:


display('y', display_id='here');


# In[7]:


update_display('z', display_id='here')


# An example ProgressBar using these messages:

# In[8]:


import os
from binascii import hexlify

class ProgressBar(object):
    def __init__(self, capacity):
        self.progress = 0
        self.capacity = capacity
        self.width = 48
        self._display_id = hexlify(os.urandom(8)).decode('ascii')
        
    def __repr__(self):
        fraction = self.progress / self.capacity
        filled = '=' * int(fraction * self.width)
        rest = ' ' * (self.width - len(filled))
        return '[{}{}] {}/{}'.format(
            filled, rest,
            self.progress, self.capacity,
        )
    
    def display(self):
        display(self, display_id=self._display_id)
    
    def update(self):
        update_display(self, display_id=self._display_id)

bar = ProgressBar(10)
bar.display()


# Update the progress bar:

# In[9]:


import time

bar.display()

for i in range(11):
    bar.progress = i
    bar.update()
    time.sleep(0.25)