Re: Determining what parameters exist for an item

[Thomas Morley]

2016-01-24 20:15 GMT+01:00 Kieren MacMillan <address@hidden>:
> Hi again,
>
> Here’s a perfect example of what I’m talking about…
>
> For KeyCancellation, the output of Harm’s function includes
>
>  GROB-INTERFACE
>         X-extent:
>         (0.0 . 5.866662)
>
> But if I look on 
> http://www.lilypond.org/doc/v2.19/Documentation/internals/keycancellation, 
> there is no entry for the X-extent setting. And if I follow the interface 
> link to grob-interface, all it says is
>
>     X-extent (pair of numbers)
>     Extent (size) in the X direction, measured in staff-space units, relative 
> to object’s reference point.
>
> with [obviously] no specific setting for KeyCancellation.

Well, it is the _actual_ default.
KeyCancellation _can't_ have a general default of X-extent for all
possible KeyCancellations...

> Now, if I want to reduce or enlarge KeyCancellation.X-extent, knowing that 
> default is (0.0 . 5.866662)*** gives me critical information that I can 
> actually use as a reference point; without that information, the 
> trial-and-error factor increases dramatically.

Well, we have the \offset-function ...
No clue about possible limitations, though

> Thanks again, Harm. This is *extremely* helpful, and exactly solves this 
> problem which I’ve asked about on the list several times over the past few 
> years.
>
> Best regards,
> Kieren.
>
> *** I’m not sure if that strange-looking value 5.866662 is the result of some 
> calculation that is getting evaluated/resolved in order to be visible in the 
> output… but that’s of secondary concern to me as a user/tweaker.

Cheers,
  Harm