Create a sequential future whose value will be in the current R session

WARNING: This function must never be called. It may only be used with plan()

Usage

sequential(..., envir = parent.frame())

Arguments

envir

The environment from where global objects should be identified.

...

Not used.

Details

A sequential future is a future that is evaluated sequentially in the current R session similarly to how R expressions are evaluated in R. The only difference to R itself is that globals are validated by default just as for all other types of futures in this package.

This function is must not be called directly. Instead, the typical usages are:

# Evaluate futures sequentially in the current R process
plan(sequential)

Examples

## Use sequential futures
plan(sequential)

## A global variable
a <- 0

## Create a sequential future
f <- future({
  b <- 3
  c <- 2
  a * b * c
})

## Since 'a' is a global variable in future 'f' which
## is eagerly resolved (default), this global has already
## been resolved / incorporated, and any changes to 'a'
## at this point will _not_ affect the value of 'f'.
a <- 7
print(a)
#> [1] 7

v <- value(f)
print(v)
#> [1] 0
stopifnot(v == 0)