Feature tuple:format to get a format of a tuple

[oleg-jukovec]

Is your feature request related to a problem? Please describe.

We need to be able to output tuples in tt with their names in a table format. Something like this:

id	age	field
1	1	'foo'
2	2	'bar'

Describe the solution you'd like

The format could be set per tuple at now:
https://github.com/tarantool/tarantool/pull/8549/commits

I want to be able to get the format object from a tuple with Lua:

local format = tuple:format()

It will allow me to get mapping field number - field name for the tuple from the format object.

Describe alternatives you've considered

tuple:tomap() returns a field name - value, a field number - value mapping. Unfortunately, this does not allow map values by a field name - value in the field number order.

We can add the option to tuple:totable(), it looks less obvious from the user point of view.

Definition of Done

It is possible to get mapping: field name - field value in the field number order for a tuple.