These helpers are useful to make your function work generically
with quosures and raw expressions. First call get_expr() to
extract an expression. Once you're done processing the expression,
call set_expr() on the original object to update the expression.
You can return the result of set_expr(), either a formula or an
expression depending on the input type. Note that set_expr() does
not change its input, it creates a new object.
Usage
set_expr(x, value)
get_expr(x, default = x)
Value
The updated original input for set_expr(). A raw
expression for get_expr().
Arguments
x
An expression, closure, or one-sided formula. In addition,
set_expr() accept frames.
value
An updated expression.
default
A default expression to return when x is not an
expression wrapper. Defaults to x itself.
See Also
quo_get_expr() and quo_set_expr() for versions of
get_expr() and set_expr() that only work on quosures.