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Date: Fri, 30 Aug 2019 15:58:51 +0300
From: Alexander Turenko <alexander.turenko@tarantool.org>
Subject: [tarantool-patches] Re: [PATCH v2 1/3] box: rfc for stacked diagnostic area in Tarantool
Message-ID: <20190830125851.fjw5wgvchuwsens6@tkn_work_nb>
References: <cover.1566553968.git.kshcherbatov@tarantool.org>
 <7b663975f0307541a6751bde10547fc2c13b5679.1566553968.git.kshcherbatov@tarantool.org>
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To: Kirill Shcherbatov <kshcherbatov@tarantool.org>
Cc: tarantool-patches@freelists.org, georgy@tarantool.org, kostja@tarantool.org

> +### Lua API
> +Tarantool returns a last-set (diag::last) error object as `cdata` from central diagnostic
> +area to Lua in case of error. User shouldn't have an ability to modify it
> +(because he actually needn't and because it is dangerous - he doesn't own this object),
> +but it need an ability to inspect a collected diagnostics information.
> +
> +Let's extend the `box.error` API with a couple of new functions:
> +1) `prev` that allows to get a reason of given error:
> +
> +```
> +-- Return a reason error object for given error
> +-- (when exists, nil otherwise)
> +box.error.prev(error)
> +```

I would also add err:prev() method like we did for, say,
box.tuple.update(t, <...>) and t:update(<...>).