Wrapper has the same interface as the wrapped function

[krlmlr]

Also, the wrapped function is referred to by memoised_function, which is clearer than f.

Cc @maxheld83 and @piccolbo.

Fixes #12.

Fixes #6.

Closes #7 (=supersedes it).

Closes #2 (=includes it).

Closes #13 (=includes it).

Example:

> memoize(runif)
function (n, min = 0, max = 1) 
{
    hash <- digest(list(n, min, max))
    if (cache$has_key(hash)) {
        res <- cache$get(hash)
    }
    else {
        res <- withVisible(memoised_function(n = n, min = min, 
            max = max))
        cache$set(hash, res)
    }
    if (res$visible) {
        res$value
    }
    else {
        invisible(res$value)
    }
}
<environment: 0x3c32040>
attr(,"memoised")
[1] TRUE
> memoize(paste)
function (..., sep = " ", collapse = NULL) 
{
    hash <- digest(list(..., sep, collapse))
    if (cache$has_key(hash)) {
        res <- cache$get(hash)
    }
    else {
        res <- withVisible(memoised_function(... = ..., sep = sep, 
            collapse = collapse))
        cache$set(hash, res)
    }
    if (res$visible) {
        res$value
    }
    else {
        invisible(res$value)
    }
}
<environment: 0x3d687f0>
attr(,"memoised")
[1] TRUE

[krlmlr]

Now complete, including revdep-check. If the memoized function is not yet defined during memoization, its formals cannot be queried, and the old implementation is used (with a warning). Ironically, the package that pointed me at that issue -- lubridate -- doesn't use memoise anymore. (It still fails, but this is due to locale settings on my machine.)

The individual merges (excluding trivial ones, oldest first) provide additional detail.

[hadley]

Is there a reason you don't want to use exists here?

[krlmlr]

I think exists() won't work with anonymous functions.

[krlmlr]

Thanks for the review, I have addressed all remarks. The most recent changes are https://github.com/krlmlr/memoise/pull/16/files.

[krlmlr]

Just updated the revdep check. Hope there won't be too many conflicts with @jimhester's pull requests.

[jimhester]

Thanks Kirill, this makes the interface much nicer!