Coerce object to quosure

Source: R/quo.R

While new_quosure() wraps any R object (including expressions, formulas, or other quosures) into a quosure, as_quosure() converts formulas and quosures and does not double-wrap.

as_quosure(x, env = NULL)

new_quosure(expr, env = caller_env())

Arguments

x

An object to convert. Either an expression or a formula.
env

The environment in which the expression should be evaluated. Only used for symbols and calls. This should typically be the environment in which the expression was created.
expr

The expression wrapped by the quosure.

Life cycle

  • as_quosure() now requires an explicit default environment for creating quosures from symbols and calls.

  • as_quosureish() is deprecated as of rlang 0.2.0. This function assumes that quosures are formulas which is currently true but might not be in the future.

See also

quo(), is_quosure()

Examples

# as_quosure() converts expressions or any R object to a validly
# scoped quosure:
env <- env(var = "thing")
as_quosure(quote(var), env)
#> <quosure>
#> expr: ^var
#> env:  0x560eadc26e60


# The environment is ignored for formulas:
as_quosure(~foo, env)
#> <quosure>
#> expr: ^foo
#> env:  0x560eadbc7298
as_quosure(~foo)
#> <quosure>
#> expr: ^foo
#> env:  0x560eadbc7298

# However you must supply it for symbols and calls:
try(as_quosure(quote(var)))
#> Warning: `as_quosure()` requires an explicit environment as of rlang 0.3.0.
#> Please supply `env`.
#> This warning is displayed once per session.
#> <quosure>
#> expr: ^var
#> env:  0x560eadbc7298