rlang (version 0.2.2)

as_quosure: Coerce object to quosure

Description

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.

Usage

as_quosure(x, env = caller_env())
new_quosure(expr, env = caller_env())

Arguments

x

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

env

The original context of the context expression.

expr

The expression wrapped by the quosure.

Life cycle

• Like the rest of the rlang package, new_quosure() and as_quosure() are maturing.

• 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

# NOT RUN {
# as_quosure() converts expressions or any R object to a validly
# scoped quosure:
as_quosure(quote(expr), base_env())
as_quosure(10L, base_env())


# Sometimes you get unscoped formulas because of quotation:
f <- ~~expr
inner_f <- f_rhs(f)
str(inner_f)

# In that case testing for a scoped formula returns FALSE:
is_formula(inner_f, scoped = TRUE)

# With as_quosure() you ensure that this kind of unscoped formulas
# will be granted a default environment:
as_quosure(inner_f, base_env())
# }