[erlang-questions] Changing the representation of sets

Andreas Schultz <>
Wed Apr 26 08:32:41 CEST 2017


Hi,

----- On Apr 25, 2017, at 1:17 PM, Attila Rajmund Nohl  wrote:

[...]

> It would affect everybody who saves the opaque data using an earlier
> OTP version, then reads it in newer OTP version (e.g. after upgrade).

That's easily solved by having the sets module accept the old representation
and convert it on the fly.

> Or those who run two nodes on different OTP versions (e.g. during an
> upgrade).

That is a different beast. One to solve it would be to not automatically
convert between old and new representation. Keep the old structure (and
code) and add a parameter to all function converting to sets to choose
between the old and new internal representation.

We could also have some global setting telling the sets to module to
auto-convert or not (defaulting to "do not convert).

Andreas


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