callHooks

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Call hook functions by hook name

Call hook functions by hook name.

Keywords
programming
Usage
# S3 method for default
callHooks(hookName, ..., removeCalledHooks=FALSE)
Arguments
hookName

A character string of the hook name.

...

Argument passed to each hook function.

removeCalledHooks

If TRUE, called hook functions are removed, otherwise not.

Value

Returns (invisibly) whatever callHooks.list() returns.

See Also

Internally, after retrieving hook functions, callHooks.list() is called.

Aliases
  • callHooks.default
  • callHooks
Examples
# NOT RUN {
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Example 1
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# First, clean up if called more than once
setHook("myFunction.onEnter", NULL, action="replace")
setHook("myFunction.onExit", NULL, action="replace")

runConference <- function(...) {
  callHooks("myFunction.onEnter")
  cat("Speaker A: Hello there...\n")
  callHooks("myFunction.onExit")
}

setHook("myFunction.onEnter", function(...) {
  cat("Chair: Welcome to our conference.\n")
})

setHook("myFunction.onEnter", function(...) {
  cat("Chair: Please welcome Speaker A!\n")
})

setHook("myFunction.onExit", function(...) {
  cat("Chair: Please thanks Speaker A!\n")
})

runConference()


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Example 2
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
setHook("randomNumber", NULL, action="replace")
setHook("randomNumber", rnorm)      # By function
setHook("randomNumber", "rexp")     # By name
setHook("randomNumber", "runiff")   # Non-existing name
setHook("randomNumber", .GlobalEnv) # Not a function

res <- callHooks("randomNumber", n=1)
str(res)
cat("Number of hooks: ", length(res), "\n");
isErroneous <- unlist(lapply(res, FUN=function(x) !is.null(x$exception)));
cat("Erroneous hooks: ", sum(isErroneous), "\n");


# }
Documentation reproduced from package R.utils, version 2.8.0, License: LGPL (>= 2.1)

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