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6.7 The dependency hierarchy and functions

The dependency hierarchy (d-hierarchy) is another structure of GOs in one page. If a GO1's anchor hangs on GO2's hanger, then GO1 is d-smaller than GO2 and GO1 is a d-child of GO2.

The d-hierarchy is an ordering over objects of the go kind in one page. This ordering can be also viewed as a directed acyclic graph (where nodes are objects of the go type).

(d-parent go id)
go symbol -> go

Returns the go's parent which is accessible through the anchor named id.

(d-children go id)
go symbol -> list

Returns the subset of go's children which are accessible through the hanger named id.

(d-all-parents go)
go -> list
Returns all parents of go.

(d-all-children go)
go -> list
Returns all children of go.

(d-set-parent! g1 k1 g2 k2)
go symbol go symbol -> unspecified
Rehangs g1's anchor named k1 on g2's hanger named k2, so g2 becomes a parent of g1. Must be called in an appropriate transaction.