# Operator on Userdata Objects

Owned by Aryn Wiebe
Last updated: Dec 04, 2023
1 min read

The # operator works on some User data type objects.

In Iguana, HL7 and X12 data are of the User data type. We generate these by parsing HL7/X12 using VMD files which define the message schemas.

Think an an HL7 message as a tree of nodes with children. The # operator gives the number of children for that node. What those children are depends on the node type.

For example:

  • For a segment it would be the number of fields

  • For a message it would be the number of segments and segment groups and arrays of segments.

Lua gives us a consistent syntax with # which is also used in these places:

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