Does mi.load_dict support another dictionary as one of the values?

[Theo-Wu]

Summary

When I tried to use mi.load_dict to load a python dictionary that contains another dictionary as a value, an error occurred: ​[xml_v.cpp:127] Missing key 'type' in the dictionary.

System configuration

OS: Ubuntu 20.04.4 LTS
CPU: Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz
GPU: NVIDIA GeForce GTX 1660 SUPER
Python: 3.9.7 (default, Sep 16 2021, 13:09:58) [GCC 7.5.0]
NVidia driver: 511.65
CUDA: 11.6.124
LLVM: 12.0.0

Dr.Jit: 0.2.2
Mitsuba: 3.0.2
Is custom build? False
Compiled with: GNU 10.2.1
Variants:
scalar_rgb
scalar_spectral
cuda_ad_rgb
llvm_ad_rgb

Description

I was customizing a python plugin for my bsdf, and I wanted to pass a dictionary as one of the properties.

Steps to reproduce

b = {
    'prop1':1,
    'a':{'prop2':2}
}
mi.load_dict(b)

[njroussel]

Hi @Theo-Wu

Yes, sort of.

If you take a look at some of the existing plugins examples, like here, the dictionary can have nested dictionaries.
However, every single dictionary level should have at least one key type, which defines the plugin type. So, effectively, you can only have nested plugins and not a "raw" dictionnary as a plugin property/parameter.

Does this make sense?