[Rd] Possible changes to connections

mel mel at altk.com
Fri Jun 1 08:24:14 CEST 2007

Prof Brian Ripley a écrit :

>> I use getConnection().
>> In the context in which I use it, the number of the connection is
>> known a priori.
> I don't see how you can know it 'a priori': it is an implementation detail
> (and since R itself uses connections, those details could easily change).

(disclaimer : I don't claim its the best way to proceed)

Before launching my app, the connections context is :
 > showConnections(all=TRUE)
   description class      mode text   isopen   can read can write
0 "stdin"     "terminal" "r"  "text" "opened" "yes"    "no"
1 "stdout"    "terminal" "w"  "text" "opened" "no"     "yes"
2 "stderr"    "terminal" "w"  "text" "opened" "no"     "yes"

So, the call to socketConnections() creates always (at least
for all my experiments) a connection with number 3.
Btw, if (socketConnections(...) != 3) the application simply
don't launch.
So, if the application runs, it's sure that this is with a
connection number==3.
That's why I say that "the number of the connection is known a priori".

Of course, the connection number could also be retrieved eg using
the description field.

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