Writing code that uses tqdm but seamlessly avoids it if tqdm is not installed

Question

I want to write a python code that uses tqdm for showing a progress bar, but if tqdm is not available then my code should just run without using tqdm's progress bar and without raising an ImportError exception;

For example, when tqdm is available it should behave like this:

from tqdm import tqdm

def my_code(items):
    for item in tqdm(items, unit='item'):
        print(item)

..and when tqdm is not available it should behave like this:

def my_code(items):
    for item in items:
        print(item)

How can I do this?

I tried just wrapping the import line:

try:
    from tqdm import tqdm
except ImportError:
    pass

..but that did not prevent a NameError from appearing on the "for item in tqdm" line. I can wrap that line with a try catch as well.. but that just make it ugly :(

def my_code(items):
    try:
        tqdm_wrapper_if_exists = tqdm(items, unit='item')
    except NameError:
        tqdm_wrapper_if_exists = items
    for item in tqdm_wrapper_if_exists:
        print(item)

I want something that I can do it one place near the import error, and let the rest of the code run seamlessly without having to be adapted.

I also looked at Create a pass-through for an installed module to achieve an optional import but the question itself assumed creating a new tqdm.py file and adding it to the system path.. which makes the ugly I was trying to avoid even more vivid :) Moreover, the solutions discussed there does not allow to write the code seamlessly beyond the import statement, because you need to copy your tqdm.py file and add it to your path. I am looking for a much cleaner solution.

Answer 1

Here's a simple solution:

try:
    from tqdm import tqdm
except ImportError:
    def tqdm(iterable, **kwargs):
        return iterable

this allows any code from that point to use tqdm when it is available, or to skip tqdm if it is not available.