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Get the future of a future variable

Source: R/delayed_api-futureOf.R
futureOf.Rd

Get the future of a future variable that has been created directly or indirectly via future().

Usage

futureOf(
  var = NULL,
  envir = parent.frame(),
  mustExist = TRUE,
  default = NA,
  drop = FALSE
)

Arguments

var

the variable. If NULL, all futures in the environment are returned.

envir

the environment where to search from.

mustExist

If TRUE and the variable does not exists, then an informative error is thrown, otherwise NA is returned.

default

the default value if future was not found.

drop

if TRUE and var is NULL, then returned list only contains futures, otherwise also default values.

Value

A Future (or default). If var is NULL, then a named list of Future:s are returned.

Examples

a %<-% { 1 }

f <- futureOf(a)
print(f)
#> SequentialFuture:
#> Label: <unnamed-12>
#> Expression:
#> {
#>     1
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-12
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.004527807 secs (started 2025-08-26 12:02:12.720688)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee

b %<-% { 2 }

f <- futureOf(b)
print(f)
#> SequentialFuture:
#> Label: <unnamed-13>
#> Expression:
#> {
#>     2
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-13
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002702951 secs (started 2025-08-26 12:02:12.733371)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee

## All futures
fs <- futureOf()
print(fs)
#> $a
#> SequentialFuture:
#> Label: <unnamed-12>
#> Expression:
#> {
#>     1
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-12
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.004527807 secs (started 2025-08-26 12:02:12.720688)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee
#> 
#> $b
#> SequentialFuture:
#> Label: <unnamed-13>
#> Expression:
#> {
#>     2
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-13
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002702951 secs (started 2025-08-26 12:02:12.733371)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee
#> 
#> $f
#> SequentialFuture:
#> Label: <unnamed-13>
#> Expression:
#> {
#>     2
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-13
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002702951 secs (started 2025-08-26 12:02:12.733371)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee
#> 


## Futures part of environment
env <- new.env()
env$c %<-% { 3 }

f <- futureOf(env$c)
print(f)
#> SequentialFuture:
#> Label: <unnamed-14>
#> Expression:
#> {
#>     3
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-14
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002790928 secs (started 2025-08-26 12:02:12.747394)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee

f2 <- futureOf(c, envir = env)
print(f2)
#> SequentialFuture:
#> Label: <unnamed-14>
#> Expression:
#> {
#>     3
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-14
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002790928 secs (started 2025-08-26 12:02:12.747394)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee

f3 <- futureOf("c", envir = env)
print(f3)
#> SequentialFuture:
#> Label: <unnamed-14>
#> Expression:
#> {
#>     3
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-14
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002790928 secs (started 2025-08-26 12:02:12.747394)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee

fs <- futureOf(envir = env)
print(fs)
#> $c
#> SequentialFuture:
#> Label: <unnamed-14>
#> Expression:
#> {
#>     3
#> }
#> Globals: <none>
#> Packages: <none>
#> L'Ecuyer-CMRG RNG seed: <none> (seed = FALSE)
#> Capture standard output: TRUE
#> Capture condition classes: ‘condition’ (excluding ‘<none>’)
#> Immediate condition classes: ‘immediateCondition’
#> Lazy evaluation: FALSE
#> Local evaluation: TRUE
#> Asynchronous evaluation: TRUE
#> Early signaling: FALSE
#> Environment: 0x5a1846057808
#> State: ‘finished’
#> Resolved: TRUE
#> Unique identifier: dc79d0e897cefbc95e5acf5248a4aaee-14
#> Owner process: dc79d0e897cefbc95e5acf5248a4aaee
#> Class: ‘SequentialFuture’, ‘UniprocessFuture’, ‘Future’
#> Value: 39 bytes of class ‘numeric’
#> Duration: 0.002790928 secs (started 2025-08-26 12:02:12.747394)
#> Worker process: dc79d0e897cefbc95e5acf5248a4aaee
#>