Standardise internal variable names in Settings code about online-go.com

[GreenAsJade]

In general, I think this ticket is aimed at code like this

    const [variation_stone_transparency, _setVariationStoneTransparency] = usePreference(
        "variation-stone-transparency",
    );

    function setVariationStoneTransparency(ev) {
        const value = parseFloat(ev.target.value);

        if (value >= 0.0 && value <= 1.0) {
            _setVariationStoneTransparency(value);
        }
    }

... where the correct function to call to set the value is setVariationStoneTransparency, then the underlying preference setter should be preceded by _

As Andy commented - "a common pattern in Prefs, but possibly elsewhere"

[GreenAsJade]

I think the gist of this ticket was "there's meaning behind the scheme, but it's inconsistently applied, so a first-time coder could get to know the code and make it applied consistently"

[anoek]

Well, what's here is the expectation that for a given state/preference xyz there exists a corresponding function setXyz that changes that value. In the case where we need some extra logic, we provide setXyz as the function we use, but we have _setXyz that that function calls after doing whatever special logic it needs. In this case, having the _setXyz is "internal" in the sense that it is not meant to be directly called by ourselves, but it remains very clear that that is the actual setter, but that we should be using setXyz.

[anoek]

Closing as "there's meaning behind the scheme and we like it as is" :)

[anoek]

In that case, open for business!