[R] Function redefinition - not urgent, but I am curious

[Peter Dalgaard]

Richard.Cotton at hsl.gov.uk wrote:
>> Suppose I write:
>>
>> f1 <- function(x) x + 1
>> f2 <- function(x) 2 * f1(x)
>> f2(10)
>> # 22
>> f1 <- function(x) x - 1
>> f2(10)
>> # 18
>>
>> This is quite obvious. But is there any way to define f2
>> in such a way that we "freeze" the definition of f1?
>>     
>
> f1 <- function(x) x+1
> f1frozen <- f1
> f2 <- function(x) 2*f1frozen(x)
> f2(10)  # 22
> f1 <- function(x) x-1
> f2(10)  # 22
>   
> f1 <- function(x) x+1
> f2 <- local({f1 <- f1; function(x) 2 * f1(x)})
> f2(10)
[1] 22
> f1 <- function(x) x-1
> f2(10)
[1] 22

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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