### 3.2.89 pure-from-neighbor-interface

A collection of routines to allow for objects’ pureheights and heights to be calculated based on theheights of the objects’ neighbors.

#### Internal properties:

> `neighbors` (array of grobs)

>   The X-axis neighbors of a grob. Used by the pure-from-neighbor-interface to determine various grob heights.

> `pure-relevant-grobs` (array of grobs)

>   All the grobs (items and spanners) that are relevant for finding the `pure-Y-extent`

> `pure-Y-common` (graphical (layout) object)

>   A cache of the `common_refpoint_of_array` of the `elements` grob set.

This grob interface is used in the following graphical object(s): BarLine, Clef, CueClef, CueEndClef, KeyCancellation, KeySignature, SpanBarStub and TimeSignature.

#### Internals Reference v2.18.2 (稳定分支).