El lun., 10 sept. 2018 a las 14:18, Tomas Kalibera
() escribió:
>
> On 09/05/2018 11:18 AM, Iñaki Ucar wrote:
> > The bottomline here is that one can always call a base method,
> > inexpensively and without modifying the object, in, let's say,
> > *formal* OOP languages. In R, this is not possible
On 09/05/2018 11:18 AM, Iñaki Ucar wrote:
The bottomline here is that one can always call a base method,
inexpensively and without modifying the object, in, let's say,
*formal* OOP languages. In R, this is not possible in general. It
would be possible if there was always a foo.default, but
On Wed, 5 Sep 2018, Kevin Ushey wrote:
More generally, I think one of the issues is that R is not yet able to
decrement a reference count (or mark a 'shared' data object as
'unshared' after it knows only one binding to it exists). This means
passing variables to R closures will mark that object
More generally, I think one of the issues is that R is not yet able to
decrement a reference count (or mark a 'shared' data object as
'unshared' after it knows only one binding to it exists). This means
passing variables to R closures will mark that object as shared:
x <- list()
The bottomline here is that one can always call a base method,
inexpensively and without modifying the object, in, let's say,
*formal* OOP languages. In R, this is not possible in general. It
would be possible if there was always a foo.default, but primitives
use internal dispatch.
I was
On 08/24/2018 07:55 PM, Henrik Bengtsson wrote:
Is there a low-level function that returns the length of an object 'x'
- the length that for instance .subset(x) and .subset2(x) see? An
obvious candidate would be to use:
.length <- function(x) length(unclass(x))
However, I'm concerned that
On 09/03/2018 03:59 PM, Dénes Tóth wrote:
Hi Tomas,
On 09/03/2018 11:49 AM, Tomas Kalibera wrote:
Please don't do this to get the underlying vector length (or to
achieve anything else). Setting/deleting attributes of an R object
without checking the reference count violates R semantics, which
Hi Tomas,
On 09/03/2018 11:49 AM, Tomas Kalibera wrote:
Please don't do this to get the underlying vector length (or to achieve
anything else). Setting/deleting attributes of an R object without
checking the reference count violates R semantics, which in turn can
have unpredictable results on
Regarding the discussion of getting length(unclass(x)) without an
unclassed version of x being created...
There are already no copies done for length(unclass(x)) in pqR
(current version of 2017-06-09 at pqR-project.org, as well as the
soon-to-be-release new version). This is part of a more
Please don't do this to get the underlying vector length (or to achieve
anything else). Setting/deleting attributes of an R object without
checking the reference count violates R semantics, which in turn can
have unpredictable results on R programs (essentially undebuggable
segfaults now or
For the new vctrs::records class, I implemented length, names, [[, and
[[<- myself in https://github.com/r-lib/vctrs/blob/master/src/fields.c.
That lets me override the default S3 methods while still being able to
access the underlying data that I'm interested in.
Another option that avoids (that
The solution below introduces a dependency on data.table, but otherwise
it does what you need:
---
# special method for Foo objects
length.Foo <- function(x) {
length(unlist(x, recursive = TRUE, use.names = FALSE))
}
# an instance of a Foo object
x <- structure(list(a = 1, b = list(b1 = 1,
Is there a low-level function that returns the length of an object 'x'
- the length that for instance .subset(x) and .subset2(x) see? An
obvious candidate would be to use:
.length <- function(x) length(unclass(x))
However, I'm concerned that calling unclass(x) may trigger an
expensive copy
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