python notes @pythonnotes tweet - When you set default value to field using a mutable object like list or dictionary, a ValueError will come out. Use default_factory instead. #Python https://t.co/NVbsmTrhbY

python notes

@pythonnotes

3 years

When you set default value to field using a mutable object like list or dictionary, a ValueError will come out. Use default_factory instead. #Python

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python notes

@pythonnotes

3 years

Because dataclasses just use normal Python class creation so two instances of class ABC share the same class variable a, which might not be a desired behavior in a dataclass, so it raises a ValueError to avoid this.