dots | R Documentation |
d <- dots(a = one, b = two)
captures each of its arguments,
unevaluated, in a dots object (a named list of quotations).
as.data.frame.dots
transforms the contents of a dots object
into a data frame with one row per quotation, with columns:
name
: a character,
expr
: an expression,
env
: an environment object or NULL if forced,
value
: NULL or a value if forced.
forced_dots(...)
forces its arguments and constructs a dots
object with
forced quotations.
forced_dots_(values)
creates a dots object from a list of values
dots(...)
dots_(exprs, envs)
exprs(d)
## S3 method for class 'dots'
exprs(d)
exprs(d) <- value
## S3 replacement method for class 'dots'
exprs(d) <- value
envs(d)
## S3 method for class 'dots'
envs(d)
envs(d) <- value
## S3 method for class 'dots'
x[..., drop = FALSE]
## S3 replacement method for class 'dots'
x[...] <- value
## S3 method for class 'dots'
c(...)
## S3 method for class 'quotation'
c(...)
## S3 method for class 'dots'
as.data.frame(x, row.names = NULL, ...)
forced_dots(...)
forced_dots_(values)
... |
Any number of arguments. |
exprs |
An expression or list of expressions. |
envs |
An environment or list of environments. |
d |
A dots object. |
value |
A replacement value or list of values. |
x |
A |
drop |
See Extract. |
row.names |
If not given, uses |
values |
A list; each element will be used as data. |
Objects of class "dots" mirror R's special variable ...
.
Unlike ...
, a dots
is:
immutable (evaluating does not change it),
first-class (you can give it any name, not just ...
),
data (The R interpreter treates it as literal data rather than triggering argument splicing).
d <- dots(...)
is used to capture the contents of ...
without
triggering evaluation. This improves on
as.list(substitute(...()))
by capturing the environment of each
argument along with their expressions. (You can also use
get_dots()
.)
dots(...)
constructs a list with class 'dots', each
element of which is a quotation.
dots_(exprs, envs)
constructs a dots object given lists
of expressions and environments. (To construct a dots object from
quotation objects, use c()
.)
exprs(d)
extracts a list of expressions from a dots object.
The mutator exprs(d) <- value
returns a new dots object
with the new expressions.
envs(d)
extracts a list of environments from a dots
object.
envs(d)
returns a named list of environments.
envs(d) <- value
returns an updated dots object with the
environments replaced with the new value(s).
as.data.frame.dots
returns a data frame.
The columns have a class "oneline"
for better printing.
named.list <- function(...) {
# Collect only named arguments, ignoring unnamed arguments.
d <- dots(...)
do(list, d[names(d) != ""])
}
named.list(a=1, b=2*2, stop("this is not evaluated"))
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