Error in Creating Custom Writer

[dmendez2]

File name

<04-Custom-Actions-In-Python/05-Custom-Writer.ipynb>

Description

<When running the notebook, there appears to be some issue with the HDF5 Writer Class. There are several chains of errors which occur. The first being: Exception ignored in: <function Simulation.__del__ at 0x7e570ab59b20> When` calling the del function, there is an error called that it cannot delete None type. The full error message is:

Exception ignored in: <function Simulation.__del__ at 0x7e570ab59b20>
Traceback (most recent call last):
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/simulation.py", line 567, in __del__
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/operations.py", line 228, in _unschedule
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/operation.py", line 256, in _detach
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/operation.py", line 366, in _unapply_typeparam_dict
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/data/typeparam.py", line 264, in _detach
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/data/parameterdicts.py", line 537, in _detach
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/data/parameterdicts.py", line 444, in _single_getitem
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/data/parameterdicts.py", line 500, in _validate_values
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/data/parameterdicts.py", line 74, in _raise_if_required_arg
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/hoomd/util.py", line 23, in _is_iterable
TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union
Exception ignored in: <function HDF5Writer.__del__ at 0x7e56d981d120>
Traceback (most recent call last):
  File "/home/user/sticky_particles/hoomd_custom_writer_tutorial.py", line 90, in __del__
  File "/home/user/sticky_particles/sticky_venv/lib/python3.12/site-packages/h5py/_hl/files.py", line 629, in close
TypeError: bad operand type for unary ~: 'NoneType'
```>

## Can you fix it?

<!-- I Cannot fix it -->

[joaander]

Thanks for reporting this issue. I am not able to reproduce the error. When I execute the notebook: 04-Custom-Actions-In-Python/05-Custom-Writer.ipynb, it runs without errors and produces the expected output.

It appears that you have converted the example to a script. When running scripts, most users write separate scripts to produce and analyze the data. In separate scripts, there is no need to call

simulation.operations.writers.remove(h5_writer)
del h5_writer

because the it will be automatically closed when the first script exits and then the data will be available for the second script to read.