[Rd] how to write dput-able objects

[Vadim Organovich]

Thank you Gabor! This is very close indeed to what I need. If dput() were generic one could code dput.proto() and that would be it.

Anyway, it is so close to what I need that I should be able to hack someting to make it work for my purposes. Thanks again!

Vadim

________________________________________
From: Gabor Grothendieck [ggrothendieck at gmail.com]
Sent: Monday, February 25, 2008 12:16 PM
To: Vadim Organovich
Cc: r-devel at r-project.org
Subject: Re: [Rd] how to write dput-able objects

You might want to look at the proto package.  proto objects won't
immediately dput either but it would not be hard to convert them to
restorable character strings because the proto methods normally
have their object as their parent environment so its implicit in the
definition.  First define a proto object p with one variable 'a' and one
method 'f' and a child object, q, whose 'a' component overrides the
'a' in its parent.

> library(proto)
> p <- proto(a=1, f = function(.) .$a <- .$a + 1)
> q <- p$proto(a = 2)
> p$as.list()
$a
[1] 1

$f
function(.) .$a <- .$a + 1
<environment: 0x01d6e284>

> name.proto(p)
[1] "p"
> name.proto(p$parent.env())
[1] "R_GlobalEnv"
> q$as.list()
$a
[1] 2

> name.proto(q)
[1] "q"
> name.proto(q$parent.env())
[1] "p"

Note that the strings above have everything
you would need to restore them.  We don't
need the environment since we already know that
f's environment must be p as it belongs to p.

On Mon, Feb 25, 2008 at 12:47 PM, Vadim Organovich
<vogranovich at jumptrading.com> wrote:
> Hi,
>
> One way of doing object-oriented programming in R is to use function environment to hold object's data, see for example
> @Article{Rnews:Chambers+Lang:2001a,
>  author       = {John M. Chambers and Duncan Temple Lang},
>  title        = {Object-Oriented Programming in {R}},
>  journal      = {R News},
>  year        = 2001,
>  volume       = 1,
>  number       = 3,
>  pages        = {17--19},
>  month        = {September},
>  url        = http,
>  pdf        = Rnews2001-3
> }
>
> One deficiency of this approach is that dput() does not export all data pertained to the object. For example
>
> > objfactory <- function(nm) {
> +   list(name = function() nm)
> + }
> >
> >
> > obj <- objfactory('foo')
> >
> > obj$name()
> [1] "foo"
> > dput(obj)
> structure(list(name = function ()
> nm), .Names = "name")
> As one can see the data piece of the obj, nm='foo', is not exported. Is there a way to modify the original approach so that dput() will produce a self-sufficient dump of the object?
>
> Thanks,
> Vadim
>
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>
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