How to use formula as character vector in curve()

Question

I have a formula as a character vector and want to use it in curve .

curve(-8*cos(2*x), 0, 10) #works as expected
formula <- "-8*cos(2*x)"

# nothing works

curve(formula, 0, 10)
# Error in formula.default(x) : invalid formula

curve(eval(formula), 0, 10)
# Error in curve(eval(formula), 0, 10) : 
#  'expr' must be a function, or a call or an expression containing 'x'

curve(as.expression(formula), 0, 10)
# Error in curve(as.expression(formula), 0, 10) : 
#  'expr' must be a function, or a call or an expression containing 'x'

curve(eval(as.expression(formula)), 0, 10)
# Error in curve(eval(as.expression(formula)), 0, 10) : 
#  'expr' must be a function, or a call or an expression containing 'x'

curve(parse(text = formula), 0, 10)
# Error in curve(parse(text = formula), 0, 10) : 
#  'expr' must be a function, or a call or an expression containing 'x'

curve(eval(parse(text = formula)), 0, 10)
# Error in curve(eval(parse(text = formula)), 0, 10) : 
#  'expr' must be a function, or a call or an expression containing 'x'

My question
How can I make this work?

Answer 1

一种可能性是简单地包装在一个函数中，

curve((function(x) eval(parse(text=formula)))(x), 0, 10)