Re: Should this be applied?

[David Kastrup]

Neil Puttock <address@hidden> writes:

> On 8 August 2011 12:43, David Kastrup <address@hidden> wrote:
>
>> I have no clue what start and end are
>
> start and end are column ranks, i.e., an index to the position of a
> particular column in a score.  You can see them if you enable
> debugging for columns:
>
> \relative c' {
>   c1
> }
>
> \layout {
>   \context {
>     \Score
>     \override PaperColumn #'stencil = #ly:paper-column::print
>     \override NonMusicalPaperColumn #'stencil = #ly:paper-column::print
>   }
> }
>
>> and I have no clue what pure is.
>
> https://secure.wikimedia.org/wikipedia/en/wiki/Pure_function
>
>> But get_pure_property takes start and end as additional arguments over
>> get_property, and so does pure_is_visible.
>>
>> So from a mere text-matching hand-waving likelihood point of view, the
>> above change seems plausible.
>>
>> Is there anybody that could shed light on this?
>
> The only effect I can see is that break-visiibility won't be cached.
> There are no pure break-visibility callbacks so the start/end args
> will never be applied.

So we have a basically unpure lookup function (caching is not all that
pure, and the callback functionality could be used for impurity as well)
that is called from a pure function, and one can determine by code
review that this will not cause trouble.

It was my distrust in this sort of reasoning that made me try to remove
cases of casting away const in the first place.

-- 
David Kastrup