Set and get an expression
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.
set_expr(x, value) get_expr(x, default = x)
x |
An expression, closure, or one-sided formula. In addition,
|
value |
An updated expression. |
default |
A default expression to return when |
The updated original input for set_expr(). A raw
expression for get_expr().
quo_get_expr() and quo_set_expr() for versions of
get_expr() and set_expr() that only work on quosures.
f <- ~foo(bar) e <- quote(foo(bar)) frame <- identity(identity(ctxt_frame())) get_expr(f) get_expr(e) get_expr(frame) set_expr(f, quote(baz)) set_expr(e, quote(baz))
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