[Rd] Possible changes to connections

mel mel at altk.com
Thu May 31 09:36:43 CEST 2007

Prof Brian Ripley a écrit :

> When I originally implemented connections in R 1.2.0, I followed the model 
> in the 'Green Book' closely.  There were a number of features that forced 
> a particular implementation, and one was getConnection() that allows one 
> to recreate a connection object from a number.

I'm currently using connections (socketConnection(), etc)
and I first want to *thank you* for this nice work.
(imho, it's so much simpler than the underlying C/C++ stuff.)

> I am wondering if anyone makes use of this, and if so for what?

I use getConnection().
In the context in which I use it, the number of the connection is
known a priori.
So getConnection() is an easy way to access to the connection
for the functions which need to.
I do not however pretend this is the best way to proceed.

> It would seem closer to the R philosophy to have connection objects that 
> get garbage collected when no R object refers to them.  This would allow 
> for example
> ... readLines(con <- gzfile("foo.gz")); close(con)
> which is a little awkward but more importantly seems little understood.

There could be/was the same debate in C/C++.
That's may be just a matter of education about not forgetting
to close previously opened doors !

> What I suspect is that very few users are aware of the Green Book 
> description and so we have freedom to make some substantial changes
> to the implementation.  Both issues suggest that connection objects should 
> be based on external pointers (which did not exist way back in 1.2.0).

I'm not skilled enough for any advice here, but from a simple user
point of view, I just hope it could continue to be as simple and
practical as today.
And I renew my thanks for the existing tool (and also the rest !).

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