A cache-aware pipe that does not mask with %>%

STILL EXPERIMENTAL. THIS MAY NOT WORK AS ANTICIPATED.

lhs %C% rhs

Arguments

lhs	A value or the magrittr placeholder.
rhs	A function call using the magrittr semantics.

Details

This pipe can only be used at the start of a pipe chain, and must be preceded by Cache(...) to allow other Cache arguments to be passed.

This will take the input arguments of the first function immediately following the Cache() %C% and the entire pipe chain code, evaluate them both against the cacheRepo argument in Cache. If they exist, then the entire pipe chain will be skipped, and only the previous final result will be given. If there is no previous cached copy of the initial function's arguments, then all chain elements will be evaluated. The final result will be cached for future use. The entire chain must be identical, therefore. The required usage should be straight forward to insert into existing code that uses pipes (Cache() %C% ... remaining pipes. This is still experimental; use with care.

See also

pipe2

Examples

# dontrun{ # these can't be automatically run due to package conflicts with magrittr
tmpdir <- file.path(tempdir(), "testCache")
checkPath(tmpdir, create = TRUE)
#> [1] "/tmp/RtmpzknuyG/testCache"
a <- rnorm(10, 16) %>%
     mean() %>%
     prod(., 6)
b <- Cache(cacheRepo = tmpdir) %C% # use of the %C% pipe!
     rnorm(10, 16) %>%
     mean() %>%
     prod(., 6)
d <- Cache(cacheRepo = tmpdir) %C%
     rnorm(10, 16) %>%
     mean() %>%
     prod(., 6)
#>   loading cached result from previous 'rnorm, mean, prod' pipe sequence call, adding to memoised copy
e <- Cache(cacheRepo = tmpdir) %C%
     rnorm(10, 16) %>%
     mean() %>%
     prod(., 5) # changed
all.equal(b,d) # TRUE
#> [1] TRUE
all.equal(a,d) # different because 'a' uses a unique rnorm, 'd' uses the Cached rnorm
#> [1] "Mean relative difference: 4.957884"
               #   because the arguments to rnorm, i.e., 10 and 16, and
               #   the subsequent functions in the chain, are identical
all.equal(a,e) # different because the final function, prod, has a changed argument.
#> [1] "Mean relative difference: 3.132421"

unlink(tmpdir, recursive = TRUE)
#}