Error assert when use lazy_instance

[Joey Gao]

🐛 Bug report

when use lazy_instance as default value, there is a assert cannot satisfy

assert name not in self.__dict__

To reproduce

1. Using the CLI function

# a.py
import tensorflow as tf
from jsonargparse import lazy_instance, CLI


def func(metric: tf.keras.metrics.Metric = lazy_instance(tf.keras.metrics.AUC)):
    print(metric.metrics.name)


CLI(func)

2. print config from cli

python a.py --print_config

trace:

Traceback (most recent call last):
  File "D:\a.py", line 5, in <module>
    def func(metric: tf.keras.metrics.Metric = lazy_instance(tf.keras.metrics.AUC)):
  File "C:\Users\xx\AppData\Local\pypoetry\Cache\virtualenvs\deepmodel-jiO4NXK3-py3.10\lib\site-packages\jsonargparse\_typehints.py", line 1420, in lazy_instance
    return lazy_init_class(class_type, kwargs)
  File "C:\Users\xx\AppData\Local\pypoetry\Cache\virtualenvs\deepmodel-jiO4NXK3-py3.10\lib\site-packages\jsonargparse\_typehints.py", line 1360, in __init__
    assert name not in self.__dict__
AssertionError

when comment # assert name not in self.__dict__ it works success

metric:
  class_path: keras.metrics.AUC
  init_args:
    num_thresholds: 200
    curve: ROC
    summation_method: interpolation
    multi_label: false
    from_logits: false

-->

Expected behavior

run normaly

Environment

• jsonargparse version (e.g., 4.29.0):
• Python version (e.g., 3.10.1):
• How jsonargparse was installed (e.g. pip install jsonargparse[all]):
• OS (e.g., Linux): wsl ubuntu 20.24
• tensorflow 2.10

[Mauricio Villegas]

Thank you for reporting! I will look at it.

[Mauricio Villegas]

For now some information. That assert is there because I didn't know if it could happen, because it it did, the implementation does not currently consider it. Removing the assert wouldn't impact the CLI logic, but the lazy instance could misbehave if used. Also, the problem happens with tensorflow 2.10 but not with the latest version. Would be good to extend the implementation to consider this case. But I would do so only if I am able to write a unit test for it, and I haven't been able for the moment.

[Joey Gao]

For now some information. That assert is there because I didn't know if it could happen, because it it did, the implementation does not currently consider it. Removing the assert wouldn't impact the CLI logic, but the lazy instance could misbehave if used. Also, the problem happens with tensorflow 2.10 but not with the latest version. Would be good to extend the implementation to consider this case. But I would do so only if I am able to write a unit test for it, and I haven't been able for the moment.

@mauvilsa Hi mauvilsa! Where can I find lazy_instance useage example for CLI, I can hardly find any infomation from documentation.

[Mauricio Villegas]

Well, there isn't much to illustrate about lazy_instance. It just creates a class instance delaying the __init__ call until first use. The example here at the top is just as good as the single one in the docs. The only other thing to say is that implementing a wrapper that delays __init__ for any possible class is not trivial, so there might be cases in which it doesn't work.