make BudgetItem.freq a property

This makes BudgetItem frequency arrays properties instead of attributes. As an attribute, BudgetItem.freq can be set directly but this doesn't update the precomp cache or any of the frequency arrays of the cal_objs and noise_objs for instances of Budget. This is a problem if run is called without any keyword arguments after changing freq. Now that freq is a property, the setter clears the precomp cache and recurses through the cal_objs and noise_objs if applicable.

So this works correctly now

traces1 = budget.run(freq=freq1)
budget.freq = freq2
traces2 = budget.run()

added bug label

how do you think an AttributeError would be raised here? this should only ever be called on strings, and I don't think any of their attributes are relevant to the parsing here.

If spec is not np.ndarray and is not None, then spec is not a string when entering the try block. spec.split(':') raises an AttributeError in this case. This was also previously the case and I fixed it this way when updating the rest of the frequency specification. This could also be solved by adding an else case after the case that spec is None. Open to other suggestions.

I guess this is a fix unrelated to the main change?

Yeah, not strictly related but I removed the unnecessary keyword while going through the rest of the update methods for this fix.

Why don't we make freq a read-only property? What benefit do we get from being able to change it on the fly, rather than re-instantiate the budget?

I'm trying to remember how I found this bug; I think it had something to do with an optimization. It should be a read-only property at a minimum.

approved this merge request

mentioned in commit 8356c3d9

merged