[R] Is it Possible to Create S4 Function Objects?

[Hervé Pagès]

Hi Abby,

Something along the line of:

   setClass("S4Function",
     contains="function",
     representation(name="character", more_stuff="ANY")
   )

seems to do what you want:

   f <- new("S4Function", function(a) a^2, name="square")

   # 'f' is both an S4 object and a function:
   is.object(f)
   # [1] TRUE
   is.function(f)
   # [1] TRUE

   f using name
   # [1] "square"
   f(11)
   # [1] 121

Hope this helps,

H.

On 2/12/21 1:53 PM, Abby Spurdle (/əˈbi/) wrote:
> Dear All,
> 
> I was wondering if it's possible to create S4 function objects?
> (Or S4 closures, if you prefer).
> 
> i.e.
> An R object, that is both an S4 object, and a function.
> 
> This would allow one to write:
> 
>> f <- constructor4.functionobj ()
>> f ()
>> f using slot.of.f
> 
> I've searched for this, but I can't find any examples.
> 
> If it's possible, then that leads to the question of if/how the body
> of f() could directly access the value of the slot?
> 
>> f <- function ()
>>     this using slot.of.f
> 
> I should note that the more common approach of storing values in a
> function's environment, doesn't work well for top-level objects.
> This approach is dependent on immutability of the function's data, and
> I'm reluctant to create such constraints.
> 
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> and provide commented, minimal, self-contained, reproducible code.
> 

-- 
Hervé Pagès

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