Handles

Mesh elements are addressed/accessed by handles. The handle type discriminates between different elements: vertices, faces, half-edges, edges.

Handles map to integral indices, the "conversion" must be preformed explicitly. The rationale is having different handle types for different mesh elements (e.g., vertex handles).

PMeshAttributes.isindex — Method
isindex(h::Hnd)

Is Int(h) a valid index, i.e., a positive integer?

Note

isindex(h) == true does not imply that the handle is valid, i.e., it references an isused element of managed attribute. (This cannot be decided only from the handle!)

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PMeshAttributes.Hnd — Type
Hnd{S}

defines a handle type for elements of category S, where S is typically a Symbol (e.g., Hnd{:V} for a vertex handle).

A handle is essentially an integral index type, but any use of arithmetic is undefined (e.g., there is nothing like Hnd(1) + 1).

Handles h can be converted to Int, but this must be done explicitly via convert(Int, h) or Int(h).

Handles may or may not be valid: the referenced element may or may not be isused.

Any handle that cannot be converted to a valid index (isindex are invalid.

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