!!!
now uses a combination of length()
, names()
, and [[
to splice
S3 and S4 objects. This produces more consistent behaviour than as.list()
on a wider variety of vector classes (#945, tidyverse/dplyr#4931).set_names()
, is_formula()
, and names2()
are now implemented in
C for efficiency.
The .data
pronoun now accepts symbol subscripts (#836).
Quosure lists now explicitly inherit from "list"
. This makes them
compatible with the vctrs package (#928).
All rlang options are now documented in a centralised place, see
?rlang::faq-options
(#899, @smingerson).
Fixed crash when env_bindings_are_lazy()
gets improper arguments (#923).
arg_match()
now detects and suggests possible typos in provided
arguments (@jonkeane, #798).
arg_match()
now gives an error if argument is of length greater
than 1 and doesn't exactly match the values input, similar to base
match.arg
(#914, @AliciaSchep)
:=
. This
syntax is automatically available in all functions taking dots with
list2()
and enquos()
, and thus most of the tidyverse. Note that
if you use the glue syntax in an R package, you need to import glue.A single pair of braces triggers normal glue interpolation:
```r df <- data.frame(x = 1:3)
suffix <- "foo" df %>% dplyr::mutate("var_{suffix}" := x * 2) #> x var_foo #> 1 1 2 #> 2 2 4 #> 3 3 6 ```
Using a pair of double braces is for labelling a function argument.
Technically, this is shortcut for "{as_label(enquo(arg))}"
. The
syntax is similar to the curly-curly syntax for interpolating
function arguments:
```r my_wrapper <- function(data, var, suffix = "foo") { data %>% dplyr::mutate("{{ var }}_{suffix}" := {{ var }} * 2) } df %>% my_wrapper(x) #> x x_foo #> 1 1 2 #> 2 2 4 #> 3 3 6
df %>% my_wrapper(sqrt(x)) #> x sqrt(x)_foo #> 1 1 2.000000 #> 2 2 2.828427 #> 3 3 3.464102 ```
Fixed a bug in magrittr backtraces that caused duplicate calls to appear in the trace.
Fixed a bug in magrittr backtraces that caused wrong call indices.
Empty backtraces are no longer shown when rlang_backtrace_on_error
is set.
The tidy eval .env
pronoun is now exported for documentation
purposes.
warn()
and abort()
now check that either class
or message
was supplied. inform()
allows sending empty message as it is
occasionally useful for building user output incrementally.
flatten()
fails with a proper error when input can't be flattened (#868, #885).
inform()
now consistently appends a final newline to the message
(#880).
cnd_body.default()
is now properly registered.
cnd_signal()
now uses the same approach as abort()
to save
unhandled errors to last_error()
.
Parsable constants like NaN
and NA_integer_
are now deparsed by
expr_deparse()
in their parsable form (#890).
Infix operators now stick to their LHS when deparsed by
expr_deparse()
(#890).
cnd_header()
, cnd_body()
and cnd_footer()
generics. These
are automatically called by conditionMessage.rlang_error()
, the
default method for all rlang errors.Concretely, this is a way of breaking up lazy generation of error
messages with conditionMessage()
into three independent
parts. This provides a lot of flexibility for hierarchies of error
classes, for instance you could inherit the body of an error message
from a parent class while overriding the header and footer.
The reminder to call last_error()
is now less confusing thanks to
a suggestion by @markhwhiteii.
The functions prefixed in scoped_
have been renamed to use the
more conventional local_
prefix. For instance, scoped_bindings()
is now local_bindings()
. The scoped_
functions will be
deprecated in the next significant version of rlang (0.5.0).
The .subclass
argument of abort()
, warn()
and inform()
has
been renamed to class
. This is for consistency with our
conventions for class constructors documented in
https://adv-r.hadley.nz/s3.html#s3-subclassing.
inform()
now prints messages to the standard output by default in
interactive sessions. This makes them appear more like normal output
in IDEs such as RStudio. In non-interactive sessions, messages are
still printed to standard error to make it easy to redirect messages
when running R scripts (#852).
Fixed an error in trace_back()
when the call stack contains a
quosured symbol.
Backtrace is now displayed in full when an error occurs in non-interactive sessions. Previously the backtraces of parent errors were left out.
New experimental framework for creating bulleted error messages. See
?cnd_message
for the motivation and an overwiew of the tools we
have created to support this approach. In particular, abort()
now
takes character vectors to assemble a bullet list. Elements named
x
are prefixed with a red cross, elements named i
are prefixed
with a blue info symbol, and unnamed elements are prefixed with a
bullet.
Capture of backtrace in the context of rethrowing an error from an
exiting handler has been improved. The tryCatch()
context no
longer leaks in the high-level backtrace.
Printing an error no longer recommends calling last_trace()
,
unless called from last_error()
.
env_clone()
no longer recreates active bindings and is now just an
alias for env2list(as.list(env))
. Unlike as.list()
which returns
the active binding function on R < 4.0, the value of active bindings
is consistently used in all versions.
The display of rlang errors derived from parent errors has been
improved. The simplified backtrace (as printed by
rlang::last_error()
) no longer includes the parent errors. On the
other hand, the full backtrace (as printed by rlang::last_trace()
)
now includes the backtraces of the parent errors.
cnd_signal()
has improved support for rlang errors created with
error_cnd()
. It now records a backtrace if there isn't one
already, and saves the error so it can be inspected with
rlang::last_error()
.
rlang errors are no longer formatted and saved through
conditionMessage()
. This makes it easier to use a
conditionMessage()
method in subclasses created with abort()
,
which is useful to delay expensive generation of error messages
until display time.
abort()
can now be called without error message. This is useful
when conditionMessage()
is used to generate the message at
print-time.
Fixed an infinite loop in eval_tidy()
. It occurred when evaluating
a quosure that inherits from the mask itself.
env_bind()
's performance has been significantly improved by fixing a bug
that caused values to be repeatedly looked up by name.
cnd_muffle()
now checks that a restart exists before invoking
it. The restart might not exist if the condition is signalled with a
different function (such as stop(warning_cnd)
).
trace_length()
returns the number of frames in a backtrace.
Added internal utility cnd_entrace()
to add a backtrace to a
condition.
rlang::last_error()
backtraces are no longer displayed in red.
x %|% y
now also works when y
is of same length as x
(@rcannood, #806).
Empty named lists are now deparsed more explicitly as
"<named list>"
.
Fixed chr()
bug causing it to return invisibly.
The main change of this release is the new tidy evaluation operator
{{
. This operator abstracts the quote-and-unquote idiom into a
single interpolation step:
my_wrapper <- function(data, var, by) {
data %>%
group_by({{ by }}) %>%
summarise(average = mean({{ var }}, na.rm = TRUE))
}
{{ var }}
is a shortcut for !!enquo(var)
that should be easier on
the eyes, and easier to learn and teach.
Note that for multiple inputs, the existing documentation doesn't stress enough that you can just pass dots straight to other tidy eval functions. There is no need for quote-and-unquote unless you need to modify the inputs or their names in some way:
my_wrapper <- function(data, var, ...) {
data %>%
group_by(...) %>%
summarise(average = mean({{ var }}, na.rm = TRUE))
}
.env
pronounAnother improvement to tidy evaluation should make it easier to use
the .env
pronoun. Starting from this release, subsetting an object
from the .env
pronoun now evaluates the corresponding symbol. This
makes .env
more robust, in particular in magrittr pipelines. The
following example would previously fail:
foo <- 10
mtcars %>% mutate(cyl = cyl * .env$foo)
This way, using the .env
pronoun is now equivalent to unquoting a
constant objects, but with an easier syntax:
mtcars %>% mutate(cyl = cyl * !!foo)
Note that following this change, and despite its name, .env
is no
longer referring to a bare environment. Instead, it is a special
shortcut with its own rules. Similarly, the .data
pronoun is not
really a data frame.
New pairlist2()
function with splicing support. It preserves
missing arguments, which makes it useful for lists of formal
parameters for functions.
is_bool()
is a scalar type predicate that checks whether its input
is a single TRUE
or FALSE
. Like is_string()
, it returns
FALSE
when the input is missing. This is useful for type-checking
function arguments (#695).
is_string()
gains a string
argument. is_string(x, "foo")
is a
shortcut for is_character(x) && length(x) == 1 && identical(x,
"foo")
.
Lists of quosures now have pillar methods for display in tibbles.
set_names()
now names unnamed input vectors before applying a
function. The following expressions are now equivalent:
``` letters %>% set_names() %>% set_names(toupper)
letters %>% set_names(toupper) ```
You can now pass a character vector as message argument for
abort()
, warn()
, inform()
, and signal()
. The vector is
collapsed to a single string with a "\n"
newline separating each
element of the input vector (#744).
maybe_missing()
gains a default
argument.
New functions for weak references: new_weakref()
, weakref_key()
,
weakref_value()
, and is_weakref()
(@wch, #787).
The performance of exec()
has been improved. It is now on the same
order of performance as do.call()
, though slightly slower.
call2()
now uses the new pairlist2()
function internally. This
considerably improves its performance. This also means it now
preserves empty arguments:
call2("fn", 1, , foo = )
#> fn(1, , foo = )
with_handlers()
now installs calling handlers first on the stack,
no matter their location in the argument list. This way they always
take precedence over exiting handlers, which ensures their side
effects (such as logging) take place (#718).
In rlang backtraces, the global::
prefix is now only added when
the function directly inherits from the global environment.
Functions inheriting indirectly no longer have a namespace
qualifier (#733).
options(error = rlang::entrace)
now has better support for errors
thrown from C (#779). It also saves structured errors in the error
field of rlang::last_error()
.
ns_env()
and ns_env_name()
(experimental functions) now support
functions and environments consisently. They also require an
argument from now on.
is_interactive()
is aware of the TESTTHAT
environment variable and
returns FALSE
when it is "true"
(@jennybc, #738).
fn_fmls()
and variants no longer coerce their input to a
closure. Instead, they throw an error.
Fixed an issue in knitr that caused backtraces to print even when error = TRUE
.
The return object from as_function()
now inherits from
"function"
(@richierocks, #735).
We commit to support 5 versions of R. As R 3.6 is about to be released, rlang now requires R 3.2 or greater. We're also continuing our efforts to streamline and narrow the rlang API.
modify()
and prepend()
(two experimental functions marked as in
the questioning stage since rlang 0.3.0) are now deprecated. Vector
functions are now out of scope for rlang. They might be revived in
the vctrs or funs packages.
exiting()
is soft-deprecated because with_handlers()
treats
handlers as exiting by default.
The vector constructors like lgl()
or new_logical()
are now in
the questioning stage. They are likely to be moved to the vctrs
package at some point. Same for the missing values shortcuts like
na_lgl
.
as_logical()
, as_integer()
, etc have been soft-deprecated in
favour of vctrs::vec_cast()
.
type_of()
, switch_type()
, coerce_type()
, and friends are
soft-deprecated.
The encoding and locale API was summarily archived. This API didn't bring any value and wasn't used on CRAN.
lang_type_of()
, switch_lang()
, and coerce_lang()
were
archived. These functions were not used on CRAN or internally.
Subsetting quosures with [
or [[
is soft-deprecated.
All functions that were soft-deprecated, deprecated, or defunct in previous releases have been bumped to the next lifecycle stage.
Fixed protection issue reported by rchk.
The experimental option rlang__backtrace_on_error
is no longer
experimental and has been renamed to rlang_backtrace_on_error
.
New "none" option for rlang_backtrace_on_error
.
Unary operators applied to quosures now give better error messages.
Fixed issue with backtraces of warnings promoted to error, and
entraced via withCallingHandlers()
. The issue didn't affect
entracing via top level options(error = rlang::entrace)
handling.
This patch release polishes the new backtrace feature introduced in
rlang 0.3.0 and solves bugs for the upcoming release of purrr
0.3.0. It also features as_label()
and as_name()
which are meant
to replace quo_name()
in the future. Finally, a bunch of deparsing
issues have been fixed.
entrace()
condition handler. Add this to your RProfile to
enable rlang backtraces for all errors, including warnings promoted
to errors:r
if (requireNamespace("rlang", quietly = TRUE)) {
options(error = rlang::entrace)
}
This handler also works as a calling handler:
r
with_handlers(
error = calling(entrace),
foo(bar)
)
However it's often more practical to use with_abort()
in that case:
r
with_abort(foo(bar))
with_abort()
gains a classes
argument to promote any kind of
condition to an rlang error.
New last_trace()
shortcut to print the backtrace stored in the
last_error()
.
Backtrace objects now print in full by default.
Calls in backtraces are now numbered according to their position in the call tree. The numbering is non-contiguous for simplified backtraces because of omitted call frames.
catch_cnd()
gains a classes
argument to specify which classes of
condition to catch. It returns NULL
if the expected condition
could not be caught (#696).
as_label()
and as_name()
The new as_label()
and as_name()
functions should be used instead
of quo_name()
to transform objects and quoted expressions to a
string. We have noticed that tidy eval users often use quo_name()
to
extract names from quosured symbols. This is not a good use for that
function because the way quo_name()
creates a string is not a well
defined operation.
For this reason, we are replacing quo_name()
with two new functions
that have more clearly defined purposes, and hopefully better names
reflecting those purposes. Use as_label()
to transform any object to
a short human-readable description, and as_name()
to extract names
from (possibly quosured) symbols.
Create labels with as_label()
to:
Display an object in a concise way, for example to labellise axes in a graphical plot.
Give default names to columns in a data frame. In this case, labelling is the first step before name repair.
We expect as_label()
to gain additional parameters in the future,
for example to control the maximum width of a label. The way an object
is labelled is thus subject to change.
On the other hand, as_name()
transforms symbols back to a string in
a well defined manner. Unlike as_label()
, as_name()
guarantees the
roundtrip symbol -> string -> symbol.
In general, if you don't know for sure what kind of object you're
dealing with (a call, a symbol, an unquoted constant), use
as_label()
and make no assumption about the resulting string. If you
know you have a symbol and need the name of the object it refers to,
use as_name()
. For instance, use as_label()
with objects captured
with enquo()
and as_name()
with symbols captured with ensym()
.
Note that quo_name()
will only be soft-deprecated at the next major
version of rlang (0.4.0). At this point, it will start issuing
once-per-session warnings in scripts, but not in packages. It will
then be deprecated in yet another major version, at which point it
will issue once-per-session warnings in packages as well. You thus
have plenty of time to change your code.
New is_interactive()
function. It serves the same purpose as
base::interactive()
but also checks if knitr is in progress and
provides an escape hatch. Use with_interactive()
and
scoped_interactive()
to override the return value of
is_interactive()
. This is useful in unit tests or to manually turn
on interactive features in RMarkdown outputs
calling()
now boxes its argument.
New done()
function to box a value. Done boxes are sentinels to
indicate early termination of a loop or computation. For instance,
it will be used in the purrr package to allow users to shortcircuit
a reduction or accumulation.
new_box()
now accepts additional attributes passed to structure()
.
Fixed a quotation bug with binary operators of zero or one argument
such as `/`(1)
(#652). They are now deparsed and printed
properly as well.
New call_ns()
function to retrieve the namespace of a
call. Returns NULL
if the call is not namespaced.
Top-level S3 objects are now deparsed properly.
Empty {
blocks are now deparsed on the same line.
Fixed a deparsing issue with symbols containing non-ASCII characters (#691).
expr_print()
now handles [
and [[
operators correctly, and
deparses non-syntactic symbols with backticks.
call_modify()
now respects ordering of unnamed inputs. Before this
fix, it would move all unnamed inputs after named ones.
as_closure()
wrappers now call primitives with positional
arguments to avoid edge case issues of argument matching.
as_closure()
wrappers now dispatch properly on methods defined in
the global environment (tidyverse/purrr#459).
as_closure()
now supports both base-style (e1
and e2
) and
purrr-style (.x
and .y
) arguments with binary primitives.
exec()
takes .fn
as first argument instead of f
, for
consistency with other rlang functions.
Fixed infinite loop with quosures created inside a data mask.
Base errors set as parent
of rlang errors are now printed
correctly.
The rlang API is still maturing. In this section, you'll find hard breaking changes. See the life cycle section below for an exhaustive list of API changes.
quo_text()
now deparses non-syntactic symbols with backticks:quo_text(sym("foo+"))
#> [1] "`foo+`"
This caused a number of issues in reverse dependencies as
quo_text()
tends to be used for converting symbols to strings.
quo_text()
and quo_name()
should not be used for this purpose
because they are general purpose deparsers. These functions should
generally only be used for printing outputs or creating default
labels. If you need to convert symbols to strings, please use
as_string()
rather than quo_text()
.
We have extended the documentation of ?quo_text
and ?quo_name
to
make these points clearer.
exprs()
no longer flattens quosures. exprs(!!!quos(x, y))
is now
equivalent to quos(x, y)
.
The sentinel for removing arguments in call_modify()
has been
changed from NULL
to zap()
. This breaking change is motivated
by the ambiguity of NULL
with valid argument values.
r
call_modify(call, arg = NULL) # Add `arg = NULL` to the call
call_modify(call, arg = zap()) # Remove the `arg` argument from the call
The %@%
operator now quotes its input and supports S4 objects.
This makes it directly equivalent to @
except that it extracts
attributes for non-S4 objects (#207).
Taking the env_parent()
of the empty environment is now an error.
The changes for this version are organised around three main themes: error reporting, tidy eval, and tidy dots.
abort()
now records backtraces automatically in the error object.
Errors thrown with abort()
invite users to call
rlang::last_error()
to see a backtrace and help identifying where
and why the error occurred. The backtraces created by rlang (you can
create one manually with trace_back()
) are printed in a simplified
form by default that removes implementation details from the
backtrace. To see the full backtrace, call
summary(rlang::last_error())
.abort()
also gains a parent
argument. This is meant for
situations where you're calling a low level API (to download a file,
parse a JSON file, etc) and would like to intercept errors with
base::tryCatch()
or rlang::with_handlers()
and rethrow them with
a high-level message. Call abort()
with the intercepted error as
the parent
argument. When the user prints rlang::last_error()
,
the backtrace will be shown in two sections corresponding to the
high-level and low-level contexts.
In order to get segmented backtraces, the low-level error has to be
thrown with abort()
. When that's not the case, you can call the
low-level function within with_abort()
to automatically promote
all errors to rlang errors.
The tidy eval changes are mostly for developers of data masking
APIs. The main user-facing change is that .data[[
is now an
unquote operator so that var
in .data[[var]]
is never masked by
data frame columns and always picked from the environment. This
makes the pronoun safe for programming in functions.
The !!!
operator now supports all classed objects like factors. It
calls as.list()
on S3 objects and as(x, "list")
on S4 objects.
dots_list()
gains several arguments to control how dots are
collected. You can control the selection of arguments with the same
name with .homonyms
(keep first, last, all, or abort). You can
also elect to preserve empty arguments with .preserve_empty
.
New trace_back()
captures a backtrace. Compared to the base R
traceback, it contains additional structure about the relationship
between frames. It comes with tools for automatically restricting to
frames after a certain environment on the stack, and to simplify
when printing. These backtraces are now recorded in errors thrown by
abort()
(see below).
abort()
gains a parent
argument to specify a parent error. This
is meant for situations where a low-level error is expected
(e.g. download or parsing failed) and you'd like to throw an error
with higher level information. Specifying the low-level error as
parent makes it possible to partition the backtraces based on
ancestry.
Errors thrown with abort()
now embed a backtrace in the condition
object. It is no longer necessary to record a trace with a calling
handler for such errors.
with_abort()
runs expressions in a context where all errors are
promoted to rlang errors and gain a backtrace.
Unhandled errors thrown by abort()
are now automatically saved and
can be retrieved with rlang::last_error()
. The error prints with a
simplified backtrace. Call summary(last_error())
to see the full
backtrace.
New experimental option rlang__backtrace_on_error
to display
backtraces alongside error messages. See ?rlang::abort
for
supported options.
The new signal()
function completes the abort()
, warn()
and
inform()
family. It creates and signals a bare condition.
New interrupt()
function to simulate an user interrupt from R
code.
cnd_signal()
now dispatches messages, warnings, errors and
interrupts to the relevant signalling functions (message()
,
warning()
, stop()
and the C function Rf_onintr()
). This makes
it a good choice to resignal a captured condition.
New cnd_type()
helper to determine the type of a condition
("condition"
, "message"
, "warning"
, "error"
or "interrupt"
).
abort()
, warn()
and inform()
now accepts metadata with ...
.
The data are stored in the condition and can be examined by user
handlers.
Consequently all arguments have been renamed and prefixed with a dot (to limit naming conflicts between arguments and metadata names).
with_handlers()
treats bare functions as exiting handlers
(equivalent to handlers supplied to tryCatch()
). It also supports
the formula shortcut for lambda functions (as in purrr).
with_handlers()
now produces a cleaner stack trace.
The input types of !!!
have been standardised. !!!
is generally
defined on vectors: it takes a vector (typically, a list) and
unquotes each element as a separate argument. The standardisation
makes !!!
behave the same in functions taking dots with list2()
and in quoting functions. !!!
accepts these types:
Lists, pairlists, and atomic vectors. If they have a class, they
are converted with base::as.list()
to allow S3 dispatch.
Following this change, objects like factors can now be spliced
without data loss.
S4 objects. These are converted with as(obj, "list")
before
splicing.
Quoted blocks of expressions, i.e. { }
calls
!!!
disallows:
Quoting functions used to automatically wrap language objects in
lists to make them spliceable. This behaviour is now soft-deprecated
and it is no longer valid to write !!!enquo(x)
. Please unquote
scalar objects with !!
instead.
dots_list()
, enexprs()
and enquos()
gain a .homonyms
argument to control how to treat arguments with the same name.
The default is to keep them. Set it to "first"
or "last"
to keep
only the first or last occurrences. Set it to "error"
to raise an
informative error about the arguments with duplicated names.
enexprs()
and enquos()
now support .ignore_empty = "all"
with named arguments as well (#414).
dots_list()
gains a .preserve_empty
argument. When TRUE
, empty
arguments are stored as missing arguments (see ?missing_arg
).
dots_list()
, enexprs()
and enquos()
gain a .check_assign
argument. When TRUE
, a warning is issued when a <-
call is
detected in ...
. No warning is issued if the assignment is wrapped
in brackets like { a <- 1 }
. The warning lets users know about a
possible typo in their code (assigning instead of matching a
function parameter) and requires them to be explicit that they
really want to assign to a variable by wrapping in parentheses.
lapply(list(quote(foo)), list2)
no longer evaluates foo
(#580).
You can now unquote quosured symbols as LHS of :=
. The symbol is
automatically unwrapped from the quosure.
Quosure methods have been defined for common operations like
==
. These methods fail with an informative error message
suggesting to unquote the quosure (#478, #tidyverse/dplyr#3476).
as_data_pronoun()
now accepts data masks. If the mask has multiple
environments, all of these are looked up when subsetting the pronoun.
Function objects stored in the mask are bypassed.
It is now possible to unquote strings in function position. This is
consistent with how the R parser coerces strings to symbols. These
two expressions are now equivalent: expr("foo"())
and
expr((!!"foo")())
.
Quosures converted to functions with as_function()
now support
nested quosures.
expr_deparse()
(used to print quosures at the console) now escapes
special characters. For instance, newlines now print as "\n"
(#484).
This ensures that the roundtrip parse_expr(expr_deparse(x))
is not
lossy.
new_data_mask()
now throws an error when bottom
is not a child
of top
(#551).
Formulas are now evaluated in the correct environment within
eval_tidy()
. This fixes issues in dplyr and other tidy-evaluation
interfaces.
New functions new_quosures()
and as_quosures()
to create or
coerce to a list of quosures. This is a small S3 class that ensures
two invariants on subsetting and concatenation: that each element is
a quosure and that the list is always named even if only with a
vector of empty strings.
env()
now treats a single unnamed argument as the parent of the
new environment. Consequently, child_env()
is now superfluous and
is now in questioning life cycle.
New current_env()
and current_fn()
functions to retrieve the
current environment or the function being evaluated. They are
equivalent to base::environment()
and base::sys.function()
called without argument.
env_get()
and env_get_list()
gain a default
argument to
provide a default value for non-existing bindings.
env_poke()
now returns the old value invisibly rather than the
input environment.
The new function env_name()
returns the name of an environment.
It always adds the "namespace:" prefix to namespace names. It
returns "global" instead of ".GlobalEnv" or "R_GlobalEnv", "empty"
instead of "R_EmptyEnv". The companion env_label()
is like
env_name()
but returns the memory address for anonymous
environments.
env_parents()
now returns a named list. The names are taken with
env_name()
.
env_parents()
and env_tail()
now stop at the global environment
by default. This can be changed with the last
argument. The empty
environment is always a stopping condition so you can take the
parents or the tail of an environment on the search path without
changing the default.
New predicates env_binding_are_active()
and
env_binding_are_lazy()
detect the kind of bindings in an
environment.
env_binding_lock()
and env_binding_unlock()
allows to lock and
unlock multiple bindings. The predicate env_binding_are_locked()
tests if bindings are locked.
env_lock()
and env_is_locked()
lock an environment or test if
an environment is locked.
env_print()
pretty-prints environments. It shows the contents (up
to 20 elements) and the properties of the environment.
is_scoped()
has been soft-deprecated and renamed to
is_attached()
. It now supports environments in addition to search
names.
env_bind_lazy()
and env_bind_active()
now support quosures.
env_bind_exprs()
and env_bind_fns()
are soft-deprecated and
renamed to env_bind_lazy()
and env_bind_active()
for clarity
and consistency.
env_bind()
, env_bind_exprs()
, and env_bind_fns()
now return
the list of old binding values (or missing arguments when there is
no old value). This makes it easy to restore the original
environment state:
old <- env_bind(env, foo = "foo", bar = "bar")
env_bind(env, !!!old)
env_bind()
now supports binding missing arguments and removing
bindings with zap sentinels. env_bind(env, foo = )
binds a missing
argument and env_bind(env, foo = zap())
removes the foo
binding.
The inherit
argument of env_get()
and env_get_list()
has
changed position. It now comes after default
.
scoped_bindings()
and with_bindings()
can now be called without
bindings.
env_clone()
now recreates active bindings correctly.
env_get()
now evaluates promises and active bindings since these are
internal objects which should not be exposed at the R level (#554)
env_print()
calls get_env()
on its argument, making it easier to
see the environment of closures and quosures (#567).
env_get()
now supports retrieving missing arguments when inherit
is FALSE
.
is_call()
now accepts multiple namespaces. For instance
is_call(x, "list", ns = c("", "base"))
will match if x
is
list()
or if it's base::list()
:
call_modify()
has better support for ...
and now treats it like
a named argument. call_modify(call, ... = )
adds ...
to the call
and call_modify(call, ... = NULL)
removes it.
call_modify()
now preserves empty arguments. It is no longer
necessary to use missing_arg()
to add a missing argument to a
call. This is possible thanks to the new .preserve_empty
option of
dots_list()
.
call_modify()
now supports removing unexisting arguments (#393)
and passing multiple arguments with the same name (#398). The new
.homonyms
argument controls how to treat these arguments.
call_standardise()
now handles primitive functions like ~
properly (#473).
call_print_type()
indicates how a call is deparsed and printed at
the console by R: prefix, infix, and special form.
The call_
functions such as call_modify()
now correctly check
that their input is the right type (#187).
New function zap()
returns a sentinel that instructs functions
like env_bind()
or call_modify()
that objects are to be removed.
New function rep_named()
repeats value along a character vector of
names.
New function exec()
is a simpler replacement to invoke()
(#536). invoke()
has been soft-deprecated.
Lambda functions created from formulas with as_function()
are now
classed. Use is_lambda()
to check a function was created with the
formula shorthand.
is_integerish()
now supports large double values (#578).
are_na()
now requires atomic vectors (#558).
The operator %@%
has now a replacement version to update
attributes of an object (#207).
fn_body()
always returns a {
block, even if the function has a
single expression. For instance fn_body(function(x) do())
returns
quote({ do() })
.
is_string()
now returns FALSE
for NA_character_
.
The vector predicates have been rewritten in C for performance.
The finite
argument of is_integerish()
is now NULL
by
default. Missing values are now considered as non-finite for
consistency with base::is.finite()
.
is_bare_integerish()
and is_scalar_integerish()
gain a finite
argument for consistency with is_integerish()
.
flatten_if()
and squash_if()
now handle primitive functions like
base::is.list()
as predicates.
is_symbol()
now accepts a character vector of names to mach the
symbol against.
parse_exprs()
and parse_quos()
now support character vectors.
Note that the output may be longer than the input as each string may
yield multiple expressions (such as "foo; bar"
).
parse_quos()
now adds the quosures
class to its output.
rlang 0.3.0 introduces a new warning mechanism for soft-deprecated functions and arguments. A warning is issued, but only under one of these circumstances:
library()
call.In addition, deprecation warnings appear only once per session in order to not be disruptive.
Deprecation warnings shouldn't make R CMD check fail for packages
using testthat. However, expect_silent()
can transform the warning
to a hard failure.
.data[[foo]]
is now an unquote operator. This guarantees that
foo
is evaluated in the context rather than the data mask and
makes it easier to treat .data[["bar"]]
the same way as a
symbol. For instance, this will help ensuring that group_by(df,
.data[["name"]])
and group_by(df, name)
produce the same column
name.
Automatic naming of expressions now uses a new deparser (still
unexported) instead of quo_text()
. Following this change,
automatic naming is now compatible with all object types (via
pillar::type_sum()
if available), prevents multi-line names, and
ensures name
and .data[["name"]]
are given the same default
name.
Supplying a name with !!!
calls is soft-deprecated. This name is
ignored because only the names of the spliced vector are applied.
Quosure lists returned by quos()
and enquos()
now have "list-of"
behaviour: the types of new elements are checked when adding objects
to the list. Consequently, assigning non-quosure objects to quosure
lists is now soft-deprecated. Please coerce to a bare list with
as.list()
beforehand.
as_quosure()
now requires an explicit environment for symbols and
calls. This should typically be the environment in which the
expression was created.
names()
and length()
methods for data pronouns are deprecated.
It is no longer valid to write names(.data)
or length(.data)
.
Using as.character()
on quosures is soft-deprecated (#523).
Using get_env()
without supplying an environment is now
soft-deprecated. Please use current_env()
to retrieve the current
environment.
The frame and stack API is soft-deprecated. Some of the
functionality has been replaced by trace_back()
.
The new_vector_along()
family is soft-deprecated because these
functions are longer to type than the equivalent rep_along()
or
rep_named()
calls without added clarity.
Passing environment wrappers like formulas or functions to env_
functions is now soft-deprecated. This internal genericity was
causing confusion (see issue #427). You should now extract the
environment separately before calling these functions.
This change concerns env_depth()
, env_poke_parent()
,
env_parent<-
, env_tail()
, set_env()
, env_clone()
,
env_inherits()
, env_bind()
, scoped_bindings()
,
with_bindings()
, env_poke()
, env_has()
, env_get()
,
env_names()
, env_bind_exprs()
and env_bind_fns()
.
cnd_signal()
now always installs a muffling restart for
non-critical conditions. Consequently the .mufflable
argument has
been soft-deprecated and no longer has any effect.Deprecated functions and arguments issue a warning inconditionally, but only once per session.
UQ()
and UQS()
with the rlang namespace qualifier is
deprecated as of rlang 0.3.0. Just use the unqualified forms
instead:``` # Bad rlang::expr(mean(rlang::UQ(var) * 100))
# Ok rlang::expr(mean(UQ(var) * 100))
# Good rlang::expr(mean(!!var * 100)) ```
Although soft-deprecated since rlang 0.2.0, UQ()
and UQS()
can still be used for now.
The call
argument of abort()
and condition constructors is now
deprecated in favour of storing full backtraces.
The .standardise
argument of call_modify()
is deprecated. Please
use call_standardise()
beforehand.
The sentinel
argument of env_tail()
has been deprecated and
renamed to last
.
Defunct functions and arguments throw an error when used.
as_dictionary()
is now defunct.
The experimental function rst_muffle()
is now defunct. Please use
cnd_muffle()
instead. Unlike its predecessor, cnd_muffle()
is not
generic. It is marked as a calling handler and thus can be passed
directly to with_handlers()
to muffle specific conditions (such as
specific subclasses of warnings).
cnd_inform()
, cnd_warn()
and cnd_abort()
are retired and
defunct. The old cnd_message()
, cnd_warning()
, cnd_error()
and
new_cnd()
constructors deprecated in rlang 0.2.0 are now defunct.
Modifying a condition with cnd_signal()
is defunct. In addition,
creating a condition with cnd_signal()
is soft-deprecated, please
use the new function [signal()] instead.
inplace()
has been renamed to calling()
to follow base R
terminology more closely.
We are no longer convinced these functions are the right approach but we do not have a precise alternative yet.
The functions from the restart API are now in the questioning lifecycle stage. It is not clear yet whether we want to recommend restarts as a style of programming in R.
prepend()
and modify()
are in the questioning stage, as well as
as_logical()
, as_character()
, etc. We are still figuring out
what vector tools belong in rlang.
flatten()
, squash()
and their atomic variants are now in the
questioning lifecycle stage. They have slightly different semantics
than the flattening functions in purrr and we are currently
rethinking our approach to flattening with the new typing facilities
of the vctrs package.
This is a maintenance release that fixes several garbage collection protection issues.
This is a maintenance release that fixes several tidy evaluation issues.
Functions with tidy dots support now allow splicing atomic vectors.
Quosures no longer capture the current srcref
.
Formulas are now evaluated in the correct environment by
eval_tidy()
. This fixes issues in dplyr and other tidy-evaluation
interfaces.
This release of rlang is mostly an effort at polishing the tidy evaluation framework. All tidy eval functions and operators have been rewritten in C in order to improve performance. Capture of expression, quasiquotation, and evaluation of quosures are now vastly faster. On the UI side, many of the inconveniences that affected the first release of rlang have been solved:
The !!
operator now has the precedence of unary +
and -
which
allows a much more natural syntax: !!a > b
only unquotes a
rather than the whole a > b
expression.
enquo()
works in magrittr pipes: mtcars %>% select(!!enquo(var))
.
enquos()
is a variant of quos()
that has a more natural
interface for capturing multiple arguments and ...
.
See the first section below for a complete list of changes to the tidy evaluation framework.
This release also polishes the rlang API. Many functions have been
renamed as we get a better feel for the consistency and clarity of the
API. Note that rlang as a whole is still maturing and some functions
are even experimental. In order to make things clearer for users of
rlang, we have started to develop a set of conventions to document the
current stability of each function. You will now find "lifecycle"
sections in documentation topics. In addition we have gathered all
lifecycle information in the ?rlang::lifecycle
help page. Please
only use functions marked as stable in your projects unless you are
prepared to deal with occasional backward incompatible updates.
The backend for quos()
, exprs()
, list2()
, dots_list()
, etc
is now written in C. This greatly improve the performance of dots
capture, especially with the splicing operator !!!
which now
scales much better (you'll see a 1000x performance gain in some
cases). The unquoting algorithm has also been improved which makes
enexpr()
and enquo()
more efficient as well.
The tidy eval !!
operator now binds tightly. You no longer have to
wrap it in parentheses, i.e. !!x > y
will only unquote x
.
Technically the !!
operator has the same precedence as unary -
and +
. This means that !!a:b
and !!a + b
are equivalent to
(!!a):b
and (!!a) + b
. On the other hand !!a^b
and !!a$b
are
equivalent to!!(a^b)
and !!(a$b)
.
The print method for quosures has been greatly improved. Quosures no
longer appear as formulas but as expressions prefixed with ^
;
quosures are colourised according to their environment; unquoted
objects are displayed between angular brackets instead of code
(i.e. an unquoted integer vector is shown as <int: 1, 2>
rather
than 1:2
); unquoted S3 objects are displayed using
pillar::type_sum()
if available.
New enquos()
function to capture arguments. It treats ...
the
same way as quos()
but can also capture named arguments just like
enquo()
, i.e. one level up. By comparison quos(arg)
only
captures the name arg
rather than the expression supplied to the
arg
argument.
In addition, enexprs()
is like enquos()
but like exprs()
it
returns bare expressions. And ensyms()
expects strings or symbols.
enquo()
within a magrittr pipe:select_one <- function(df, var) {
df %>% dplyr::select(!!enquo(var))
}
Technically, this is because enquo()
now also captures arguments
in parents of the current environment rather than just in the
current environment. The flip side of this increased flexibility is
that if you made a typo in the name of the variable you want to
capture, and if an object of that name exists anywhere in the parent
contexts, you will capture that object rather than getting an error.
quo_expr()
has been renamed to quo_squash()
in order to better
reflect that it is a lossy operation that flattens all nested
quosures.
!!!
now accepts any kind of objects for consistency. Scalar types
are treated as vectors of length 1. Previously only symbolic objects
like symbols and calls were treated as such.
ensym()
is a new variant of enexpr()
that expects a symbol or a
string and always returns a symbol. If a complex expression is
supplied it fails with an error.
exprs()
and quos()
gain a .unquote_names
arguments to switch
off interpretation of :=
as a name operator. This should be useful
for programming on the language targetting APIs such as
data.table.
exprs()
gains a .named
option to auto-label its arguments (#267).
Functions taking dots by value rather than by expression
(e.g. regular functions, not quoting functions) have a more
restricted set of unquoting operations. They only support :=
and
!!!
, and only at top-level. I.e. dots_list(!!! x)
is valid but
not dots_list(nested_call(!!! x))
(#217).
Functions taking dots with list2()
or dots_list()
now support
splicing of NULL
values. !!! NULL
is equivalent to !!! list()
(#242).
Capture operators now support evaluated arguments. Capturing a
forced or evaluated argument is exactly the same as unquoting that
argument: the actual object (even if a vector) is inlined in the
expression. Capturing a forced argument occurs when you use
enquo()
, enexpr()
, etc too late. It also happens when your
quoting function is supplied to lapply()
or when you try to quote
the first argument of an S3 method (which is necessarily evaluated
in order to detect which class to dispatch to). (#295, #300).
Parentheses around !!
are automatically removed. This makes the
generated expression call cleaner: (!! sym("name"))(arg)
. Note
that removing the parentheses will never affect the actual
precedence within the expression as the parentheses are only useful
when parsing code as text. The parentheses will also be added by R
when printing code if needed (#296).
Quasiquotation now supports !!
and !!!
as functional forms:
expr(`!!`(var))
quo(call(`!!!`(var)))
This is consistent with the way native R operators parses to
function calls. These new functional forms are to be preferred to
UQ()
and UQS()
. We are now questioning the latter and might
deprecate them in a future release.
The quasiquotation parser now gives meaningful errors in corner cases to help you figure out what is wrong.
New getters and setters for quosures: quo_get_expr()
,
quo_get_env()
, quo_set_expr()
, and quo_set_env()
. Compared to
get_expr()
etc, these accessors only work on quosures and are
slightly more efficient.
quo_is_symbol()
and quo_is_call()
now take the same set of
arguments as is_symbol()
and is_call()
.
enquo()
and enexpr()
now deal with default values correctly (#201).
Splicing a list no longer mutates it (#280).
The new functions cnd_warn()
and cnd_inform()
transform
conditions to warnings or messages before signalling them.
cnd_signal()
now returns invisibly.
cnd_signal()
and cnd_abort()
now accept character vectors to
create typed conditions with several S3 subclasses.
is_condition()
is now properly exported.
Condition signallers such as cnd_signal()
and abort()
now accept
a call depth as call
arguments. This allows plucking a call from
further up the call stack (#30).
New helper catch_cnd()
. This is a small wrapper around
tryCatch()
that captures and returns any signalled condition. It
returns NULL
if none was signalled.
cnd_abort()
now adds the correct S3 classes for error
conditions. This fixes error catching, for instance by
testthat::expect_error()
.
env_get_list()
retrieves muliple bindings from an environment into
a named list.
with_bindings()
and scoped_bindings()
establish temporary
bindings in an environment.
is_namespace()
is a snake case wrapper around isNamespace()
.
New functions inherits_any()
, inherits_all()
, and
inherits_only()
. They allow testing for inheritance from multiple
classes. The _any
variant is equivalent to base::inherits()
but
is more explicit about its behaviour. inherits_all()
checks that
all classes are present in order and inherits_only()
checks that
the class vectors are identical.
New fn_fmls<-
and fn_fmls_names<-
setters.
New function experimental function chr_unserialise_unicode()
for
turning characters serialised to unicode point form
(e.g. <U+xxxx>
) to UTF-8. In addition, as_utf8_character()
now
translates those as well. (@krlmlr)
expr_label()
now supports quoted function definition calls (#275).
call_modify()
and call_standardise()
gain an argument to specify
an environment. The call definition is looked up in that environment
when the call to modify or standardise is not wrapped in a quosure.
is_symbol()
gains a name
argument to check that that the symbol
name matches a string (#287).
New rlang_box
class. Its purpose is similar to the AsIs
class
from base::I()
, i.e. it protects a value temporarily. However it
does so by wrapping the value in a scalar list. Use new_box()
to
create a boxed value, is_box()
to test for a boxed value, and
unbox()
to unbox it. new_box()
and is_box()
accept optional
subclass.
The vector constructors such as new_integer()
,
new_double_along()
etc gain a names
argument. In the case of the
_along
family it defaults to the names of the input vector.
When nested quosures are evaluated with eval_tidy()
, the .env
pronoun now correctly refers to the current quosure under evaluation
(#174). Previously it would always refer to the environment of the
outermost quosure.
as_pairlist()
(part of the experimental API) now supports NULL
and objects of type pairlist (#397).
Fixed a performance bug in set_names()
that caused a full copy of
the vector names (@jimhester, #366).
The rlang API is maturing and still in flux. However we have made an
effort to better communicate what parts are stable. We will not
introduce breaking changes for stable functions unless the payoff for
the change is worth the trouble. See ?rlang::lifecycle
for the
lifecycle status of exported functions.
The particle "lang" has been renamed to "call":
lang()
has been renamed to call2()
.new_language()
has ben renamed to new_call()
.is_lang()
has been renamed to is_call()
. We haven't replaced
the is_unary_lang()
and is_binary_lang()
because they are
redundant with the n
argument of is_call()
.lang_fn()
, lang_name()
,
lang_args()
etc are soft-deprecated and renamed with call_
prefix.In rlang 0.1 calls were called "language" objects in order to follow
the R type nomenclature as returned by base::typeof()
. We wanted
to avoid adding to the confusion between S modes and R types. With
hindsight we find it is better to use more meaningful type names.
Following this new terminology, the new functions as_data_mask()
and new_data_mask()
replace as_overscope()
and
new_overscope()
. as_data_mask()
has also a more consistent
interface. These functions are only meant for developers of tidy
evaluation interfaces.
overscope_clean()
is thus
soft-deprecated without replacement.!!
now binds tightly in order to match intuitive parsing of tidy
eval code, e.g. !! x > y
is now equivalent to (!! x) > y
. A
corollary of this new syntax is that you now have to be explicit
when you want to unquote the whole expression on the right of !!
.
For instance you have to explicitly write !! (x > y)
to unquote
x > y
rather than just x
.
UQ()
, UQS()
and :=
now issue an error when called
directly. The previous definitions caused surprising results when
the operators were invoked in wrong places (i.e. not in quasiquoted
arguments).
The prefix form `!!`()
is now an alias to !!
rather than
UQE()
. This makes it more in line with regular R syntax where
operators are parsed as regular calls, e.g. a + b
is parsed as `+`(a, b)
and both forms are completely equivalent. Also the
prefix form `!!!`()
is now equivalent to !!!
.
UQE()
is now deprecated in order to simplify the syntax of
quasiquotation. Please use !! get_expr(x)
instead.
expr_interp()
now returns a formula instead of a quosure when
supplied a formula.
is_quosureish()
and as_quosureish()
are deprecated. These
functions assumed that quosures are formulas but that is only an
implementation detail.
new_cnd()
is now cnd()
for consistency with other constructors.
Also, cnd_error()
, cnd_warning()
and cnd_message()
are now
error_cnd()
, warning_cnd()
and message_cnd()
to follow our
naming scheme according to which the type of output is a suffix
rather than a prefix.
is_node()
now returns TRUE
for calls as well and is_pairlist()
does not return TRUE
for NULL
objects. Use is_node_list()
to
determine whether an object either of type pairlist
or NULL
.
Note that all these functions are still experimental.
set_names()
no longer automatically splices lists of character
vectors as we are moving away from automatic splicing semantics.
Calling the functional forms of unquote operators with the rlang
namespace qualifier is soft-deprecated. UQ()
and UQS()
are not
function calls so it does not make sense to namespace them.
Supporting namespace qualifiers complicates the implementation of
unquotation and is misleading as to the nature of unquoting (which
are syntactic operators at quotation-time rather than function calls
at evaluation-time).
We are now questioning UQ()
and UQS()
as functional forms of
!!
. If !!
and !!!
were native R operators, they would parse
to the functional calls `!!`()
and `!!!`()
. This is now
the preferred way to unquote with a function call rather than with
the operators. We haven't decided yet whether we will deprecate
UQ()
and UQS()
in the future. In any case we recommend using the
new functional forms.
parse_quosure()
and parse_quosures()
are soft-deprecated in
favour of parse_quo()
and parse_quos()
. These new names are
consistent with the rule that abbreviated suffixes indicate the
return type of a function. In addition the new functions require their
callers to explicitly supply an environment for the quosures.
Using f_rhs()
and f_env()
on quosures is soft-deprecated. The
fact that quosures are formulas is an implementation detail that
might change in the future. Please use quo_get_expr()
and
quo_get_env()
instead.
quo_expr()
is soft-deprecated in favour of quo_squash()
.
quo_expr()
was a misnomer because it implied that it was a mere
expression acccessor for quosures whereas it was really a lossy
operation that squashed all nested quosures.
With the renaming of the lang
particle to call
, all these
functions are soft-deprecated: lang()
, is_lang()
, lang_fn()
,
lang_name()
, lang_args()
.
In addition, lang_head()
and lang_tail()
are soft-deprecated
without replacement because these are low level accessors that are
rarely needed.
as_overscope()
is soft-deprecated in favour of as_data_mask()
.
The node setters were renamed from mut_node_
prefix to
node_poke_
. This change follows a new naming convention in rlang
where mutation is referred to as "poking".
splice()
is now in questioning stage as it is not needed given the
!!!
operator works in functions taking dots with dots_list()
.
lgl_len()
, int_len()
etc have been soft-deprecated and renamed
with new_
prefix, e.g. new_logical()
and new_integer()
. This
is for consistency with other non-variadic object constructors.
ll()
is now an alias to list2()
. This is consistent with the new
call2()
constructor for calls. list2()
and call2()
are
versions of list()
and call()
that support splicing of lists
with !!!
. ll()
remains around as a shorthand for users who like
its conciseness.
Automatic splicing of lists in vector constructors (e.g. lgl()
,
chr()
, etc) is now soft-deprecated. Please be explicit with the
splicing operator !!!
.
This is a maintenance release in anticipation of a forthcoming
change to R's C API (use MARK_NOT_MUTABLE()
instead of
SET_NAMED()
).
New function is_reference()
to check whether two objects are one
and the same.
eval_tidy()
no longer maps over lists but returns them literally.
This behaviour is an overlook from past refactorings and was never
documented.This hotfix release makes rlang compatible with the R 3.1 branch.
This release includes two important fixes for tidy evaluation:
Bare formulas are now evaluated in the correct environment in tidyeval functions.
enquo()
now works properly within compiled functions. Before this
release, constants optimised by the bytecode compiler couldn't be
enquoted.
The new_environment()
constructor creates a child of the empty
environment and takes an optional named list of data to populate it.
Compared to env()
and child_env()
, it is meant to create
environments as data structures rather than as part of a scope
hierarchy.
The new_call()
constructor creates calls out of a callable
object (a function or an expression) and a pairlist of arguments. It
is useful to avoid costly internal coercions between lists and
pairlists of arguments.
env_child()
's first argument is now .parent
instead of parent
.
mut_
setters like mut_attrs()
and environment helpers like
env_bind()
and env_unbind()
now return their (modified) input
invisibly. This follows the tidyverse convention that functions
called primarily for their side effects should return their input
invisibly.
is_pairlist()
now returns TRUE
for NULL
. We added is_node()
to test for actual pairlist nodes. In other words, is_pairlist()
tests for the data structure while is_node()
tests for the type.
env()
and env_child()
can now get arguments whose names start
with .
. Prior to this fix, these arguments were partial-matching
on env_bind()
's .env
argument.
The internal replace_na()
symbol was renamed to avoid a collision
with an exported function in tidyverse. This solves an issue
occurring in old versions of R prior to 3.3.2 (#133).
Initial release.
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