westonpace opened a new issue, #61:
URL: https://github.com/apache/arrow-js/issues/61
### Describe the enhancement requested
There are a number of places that arrow's js package uses `instanceof`. For
example:
```
// from table.ts in the Table constructor
if (args[0] instanceof Schema) {
schema = args.shift() as Schema<T>;
}
```
Unfortunately, this is quite brittle. This will fail whenever a library
ends up with multiple instances of the arrow library. For example:
* LanceDb currently uses arrow version 14. If the calling user is using
any other version of arrow then node will happily install two versions of arrow
and the checks will fail. (also, these failures tend to be very opaque)
* Even if the user is using the exact same version of arrow there are cases
where two instances of arrow are created. For example, our users using vite
have run into https://github.com/vitejs/vite/issues/3910
I would argue that some of the core types (at least `Schema` but maybe also
`Table` / `Vector` / `RecordBatch` too) should be considered stable and users
should be allowed to have different versions / instances. We tried working
around this in lancedb by declaring arrow a peer dependency and that solves the
first bullet above but it's also somewhat unconventional (for javascript) and
inconvenient for our users (they are forced to use whatever version of arrow we
are using and when we change our arrow version it is a breaking change).
This is not critical, we've worked around this by re-building the schema if
the input from our user looks like a schema, but I wanted to see if other JS
users/maintainers felt similarly and, if so, I might try and find some time to
explore a fix.
Some potential fixes:
* Add methods like `isArrowSchema` and use those methods instead of
`instanceof`
* Customize the definition of `instanceof` by implementing
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/hasInstance
on types like `Schema`.
* Stick with the current but upstream methods like
https://github.com/lancedb/lancedb/blob/dfc518b8fbc5920cf7dafd072335257be1e5d9c5/nodejs/lancedb/sanitize.ts#L491
so that this kind of "schema rebuild" is maintained here in arrow.
### Component(s)
JavaScript
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