prevent overwriting entity variables

[custom-components]

prevent overwriting entity variables

[craigbarratt]

I don't know why they become unavailable. Is it because the attributes get cleared when you do this?

This seems related to issue #9.

[craigbarratt]

With commit 712692f, state variable setting now preserves attributes.

[fleXible]

While playing around I came across a different problem regarding overwriting variables.
I seems, that declared variables take presedence over provided variables/objects.

Sample code:

@time_trigger
def precendce_problem():
    log.info(f"precendce_problem: running")
    event = None
    event.fire("raises Exception")

precendce_problem: running
Exception in <jupyter_0.precendce_problem> line 35:
event.fire("raises Exception")
^
AttributeError: 'NoneType' object has no attribute 'fire'

I came across this, when doing a for loop and naming the variable "state" without thinking too much about it.
It wouldn't be too much of an issue, if variables would be scoped, but as they are not, weird things can happen if you don't watch out.

[craigbarratt]

Variable scoping should be the same as Python, and I agree it would be a bug if it wasn't. If you create a local variable it will overwrite a previously defined function or object.

The example looks correct to me. This behaves exactly the same in Python and pyscript:

bytes.fromhex("1234")
bytes = None
bytes.fromhex("5678")

The first call works, and the second one fails with an error:

AttributeError: 'NoneType' object has no attribute 'fromhex'

Here's another example that also works the same in Python and pyscript:

import math
print(math.sqrt(2))
math = None
print(math.sqrt(2))

I agree there is a subtle difference in pyscript: yes, event or state don't exist as an object. But if it does (ie: you set them to something), that takes precedence over the event.fire or state.set functions, which is the same behavior as regular Python.

[fleXible]

What you say makes sense, I just never happen to stumble upon it before. Issue can be closed.