[Python] Redirect print command in python script through tqdm.write()

I'm using tqdm in Python to display console-progressbars in our scripts. However, I have to call functions which print messages to the console as well and which I can't change. In general, writing to the console while displaying progress bars in the console messes up the display like so:

from time import sleep
from tqdm import tqdm

def blabla():
print "Foo blabla"

for k in tqdm(range(3)):
blabla()
sleep(.5)


This creates the output:

0%| | 0/3 [00:00<?, ?it/s]Foo
blabla
33%|###########6 | 1/3 [00:00<00:01, 2.00it/s]Foo
blabla
67%|#######################3 | 2/3 [00:01<00:00, 2.00it/s]Foo
blabla
100%|###################################| 3/3 [00:01<00:00, 2.00it/s]


According to the documentation of tqdm the method tqdm.write() provides a means to write messages to the console without breaking the displayed progressbars. Thus, the right output is provided by this snippet:

from time import sleep
from tqdm import tqdm

def blabla():
tqdm.write("Foo blabla")

for k in tqdm(range(3)):
blabla()
sleep(.5)


And looks like this:

Foo blabla
Foo blabla
Foo blabla
100%|###################################| 3/3 [00:01<00:00, 1.99it/s]


On the other hand, there is this solution which permits to silence those functions by quite elegantly redirecting sys.stdout into the void. This works perfectly well for silencing the functions.

Since I want to display the messages from these functions nonetheless without breaking the progress bars, I tried to merge both solutions into one by redirecting sys.stdout to tqdm.write() and, in turn, letting tqdm.write() write to the old sys.stdout. This results in the snippet:

from time import sleep

import contextlib
import sys

from tqdm import tqdm

class DummyFile(object):
file = None
def __init__(self, file):
self.file = file

def write(self, x):
tqdm.write(x, file=self.file)

@contextlib.contextmanager
def nostdout():
save_stdout = sys.stdout
sys.stdout = DummyFile(save_stdout)
yield
sys.stdout = save_stdout

def blabla():
print "Foo blabla"

for k in tqdm(range(3)):
with nostdout():
blabla()
sleep(.5)


However, this actually creates an even more messed up output as before:

0%| | 0/3 [00:00<?, ?it/s]Foo
blabla


33%|###########6 | 1/3 [00:00<00:01, 2.00it/s]Foo
blabla


67%|#######################3 | 2/3 [00:01<00:00, 2.00it/s]Foo
blabla


100%|###################################| 3/3 [00:01<00:00, 2.00it/s]


FYI: calling tqdm.write(..., end="") inside DummyFile.write() creates the same result as the first output which is still messed up.

I can't understand why this wouldn't work, since tqdm.write() is supposed to manage clearing the progress bar before writing the message and then rewriting the progress bar.

What am I missing?

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