toSummaryString

One line describing this value's shape and size, whatever it holds and however large it is.

Variant(object, children=12, bytes=4200000)
Variant(array, children=1024, bytes=812)
Variant(string, bytes=104)

The child count is omitted for a scalar rather than reported as zero, for the reason ReadableBitmap.describe has two forms: children=0 on a string is noise in the one place there is no room for any. The shape rhymes with VariantMetadata.toString on purpose — these are siblings and should read like it.

Reads the header and, for a container, its last offset. Nothing else, at any size.

Never throws. A value whose bytes do not decode is described as unreadable in exactly the words Variant.toString uses for the same failure — one spelling, two callers, because a reader meeting the second should not have to wonder whether it means something different.