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Comment by drysart

There are inherent limitations with the "execute it once and see what happens" approach; namely that any conditional logic that might be in the mapping function is going to silently get ignored. For example, `db.people.map(p => p.IsPerson ? (p.FirstName + ' ' + p.LastName) : p.EntityName)` would either be seen as reading `(IsPerson, FirstName, LastName)` or `(p.IsPerson, p.EntityName)` depending on the specific behavior of the placeholder value ... and neither of those sets is fully correct.

I wonder why they don't just do `.toString()` on the mapping function and then parse the resulting Javascript into an AST and figure out property accesses from that. At the very least, that'd allow the code to properly throw an error in the event the callback contains any forbidden or unsupported constructs.

parent drysart 1 year ago

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