[erlang-questions] spawning funs on other nodes that does not contain my module

Marcel Meyer <>
Tue Nov 30 23:10:36 CET 2010


Thanks Kresten,
The bottom part of your article where you rpc:multicall the code and force
load it on each node ended up working perfectly.

You know, this stuff really is magic.

Thank you again,
Marcel

On Tue, Nov 30, 2010 at 2:19 PM, Kresten Krab Thorup <>wrote:

> Marcel,
>
> I discuss these issues at some length in this blog post:
> http://bit.ly/fQoKlu; and towards the end you'll see some code that lets
> you construct an interpreted fun, like this:
>
> 1> FunStr = "fun (A) -> A+B end.".
> 2> {ok, Tokens, _} = erl_scan:string(FunStr).
> 3> {ok, [Form]} = erl_parse:parse_exprs(Tokens).
> 4> Bindings = erl_eval:add_binding('B', 2, erl_eval:new_bindings()).
> 5> {value, Fun, _} = erl_eval:expr(Form, Bindings).
> 6> Fun(1).
> 3
>
> Such a fun should be passable between nodes, if only the target node has
> erl_eval (and related modules).  Which should be very likely, but it needs
> to be the same version of erl_eval.   It is not very fast though, but that
> may not be important to you; especially if what you want to do is something
> simple.
>
> Kresten
>
>
> On Nov 30, 2010, at 19:36 , Marcel Meyer wrote:
>
> > Hi there,
> >
> > Is it possible to spawn a function (which is pretty straight
> > forward, essentially a receive loop that grabs the message and
> > file:write_file's it to the file system) on another node, which does not
> > have a copy of my module?
> >
> > I thought I would be able to make a fun that returns the mentioned fun
> above
> > and then spawn that message sink on another node.
> >
> > I am investigating writing a file propagation system and it would be nice
> if
> > there is one process that gets notified of new files, which spawns a fun
> on
> > each recipient node, which tells that node how to handle it.
> >
> > Any insights? Or should each node be running a file sink that just
> listens
> > for these {save, Data} msgs? I am trying to write something where I dont
> > have to manage the child nodes and their code. Perhaps a file sink
> > gen_server on each node that supports upgrades?
> >
> > Regards,
> > Marcel
>
> Kresten Krab Thorup, CTO, Trifork
>
>


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