Frozen boxes are great for enforcing a functional style of programming at runtime. But the implementation of Box.__add__ assumes that the left-hand side is non-frozen.
The following piece of code fails in box/box.py:274: box.box.Box.__add__ with box.exceptions.BoxError: Box is frozen
foo = box.Box(frozen_box=True)
foobar = foo + {"bar": 1}As far as I can judge, there is no reason to restrict __add__ (and __or__) operations to non-frozen boxes. The implementation of Box.__add__ creates a copy of the input box before merging/updating, thus the operations leave the input boxes unmodified.
This implementation of Box.__or__ would solve the issue:
...
new_box = other.copy()
new_box._box_config["frozen_box"] = False
new_box.update(other)
new_box._box_config["frozen_box"] = other._box_config["frozen_box"]
...
I've made a quick check that this works for flat and nested structures. But there might be some unintended side effects for nested structures. But this would be an issue even for non-frozen boxes. I guess most programmers will assume that writing foobar = foo + {"bar": 1} won't mutate foo.
What are the objections against frozen boxes in Box.__add__ (Box.__or__)? And, how should this be implemented?
Frozen boxes are great for enforcing a functional style of programming at runtime. But the implementation of
Box.__add__assumes that the left-hand side is non-frozen.The following piece of code fails in
box/box.py:274: box.box.Box.__add__withbox.exceptions.BoxError: Box is frozenAs far as I can judge, there is no reason to restrict
__add__(and__or__) operations to non-frozen boxes. The implementation ofBox.__add__creates a copy of the input box before merging/updating, thus the operations leave the input boxes unmodified.This implementation of
Box.__or__would solve the issue:I've made a quick check that this works for flat and nested structures. But there might be some unintended side effects for nested structures. But this would be an issue even for non-frozen boxes. I guess most programmers will assume that writing
foobar = foo + {"bar": 1}won't mutate foo.What are the objections against frozen boxes in
Box.__add__(Box.__or__)? And, how should this be implemented?