Is there a way to deal with variable sized iterables?

The problem is this line:
self.total = len(gen) if total is None else total

That is executed at the beginning. But len(gen) might change throughout the iteration, but progress_bar just assumes it keeps still.

What I really want is to use a timer (so "train for 1 hour" instead of "train for so and so epochs").

import time
class Timer:
    def __init__(self, num_seconds):
        self.num_seconds = num_seconds
        self.i = None
        
    def __len__(self):
        if self.i is None: return 1
        eps = 1e-7
        t = time.time() - self.start
        progress = t/num_seconds
        return int((num_seconds*self.i)/(progress+eps)) # estimated size. Changes constantly.
    
    def __iter__(self):
        self.start = time.time()
        self.i, t = 0, 0.0
        while t <= self.num_seconds:
            t = time.time() - self.start
            self.i += 1
            yield None

With this class, if you write

for t in Timer(3.0):
    # do stuff

it runs for 3 seconds. But it doesn't work with the progress_bar :(

Commencez par localiser l’implémentation de progress_bar et la ligne self.total = len(gen) if total is None else total décrite dans l’issue. Reproduisez ensuite l’exemple de Timer fourni, puis déterminez comment les itérables de taille variable ou l’itération basée sur le temps doivent être représentés ; le travail est considéré comme terminé lorsque la barre de progression peut gérer ce cas d’utilisation sans supposer une longueur fixe.