dynamic code replacement

Ulf Wiger ulf.wiger@REDACTED
Fri May 14 10:21:03 CEST 1999

Mark NG wrote:
> G'day !
> I was wondering if there are currently any know problems or issues or gotchas
> with dynamic code replacement under Erlang.
> thanks,
> mark

Not really any issues in the sense that it wouldn't work
Dynamic code replacement can be about as easy or complex as you
want/need to make it. The easiest part is simply loading the module. For
library code, this is all that's needed.

Torbjorn Tornkvist wrote:
> Well, in the case where you are running a server. Make sure that
> you make a module prefixed recursive call to the top loop.
> Example:
> loop(Data) ->
>    receive
>       X ->
>          NewData = do_stuff(Data,X),
>          ?MODULE:loop(NewData)
>    end.

If your new version has a different representation of Data, this will
not work. For this eventuality, OTP provides a framework for performing
synchronized code change with hooks for transformation of internal

A couple of pointers:

- If you want to learn about OTP's system messages
  (Click on "Design Principles")

- If you want to learn about OTP's release handling:
  (see the User's Guide.)

Ulf Wiger, Chief Designer AXD 301     <ulf.wiger@REDACTED>
Ericsson Telecom AB                          tfn: +46  8 719 81 95
Varuvägen 9, Älvsjö                          mob: +46 70 519 81 95
S-126 25 Stockholm, Sweden                   fax: +46  8 719 43 44

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