[Rd] How do I reliably and efficiently hash a function?

[Hadley Wickham]

On Thu, Dec 10, 2015 at 5:49 PM, Konrad Rudolph
<konrad.rudolph+r-devel at gmail.com> wrote:
> I’ve got the following scenario: I need to store information about an
> R function, and retrieve it at a later point. In other programming
> languages I’d implement this using a dictionary with the functions as
> keys. In R, I’d usually use `attr(f, 'some-name')`. However, for my
> purposes I do not want to use `attr` because the information that I
> want to store is an implementation detail that should be hidden from
> the user of the function (and, just as importantly, it shouldn’t
> clutter the display when the function is printed on the console).
>
> `comment` would be almost perfect since it’s hidden from the output
> when printing a function — unfortunately, the information I’m storing
> is not a character string (it’s in fact an environment), so I cannot
> use `comment`.
>
> How can this be achieved?
>
> For reference, I’ve considered the following two alternatives:
>
> 1. Use `attr`, and override `print.function` to not print my
> attribute. However, I’m wary of overriding a core function just to
> implement such a little thing, and overriding this function would
> obviously clash with other overrides, if somebody else happens to have
> a similarly harebrain idea.

Why not use your own S3 class?

Hadley

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