R: Query the names of the current internal top-level task callbacks

taskCallbackNames {base} | R Documentation

## Query the names of the current internal top-level task callbacks

### Description

This provides a way to get the names (or identifiers) for the currently registered task callbacks that are invoked at the conclusion of each top-level task. These identifiers can be used to remove a callback.

### Usage

    getTaskCallbackNames()

### Value

A character vector giving the name for each of the registered callbacks which are invoked when a top-level task is completed successfully. Each name is the one used when registering the callbacks and returned as the in the call to `addTaskCallback`.

### Note

One can use `taskCallbackManager` to manage user-level task callbacks, i.e., S-language functions, entirely within the S language and access the names more directly.

### See Also

`addTaskCallback`, `removeTaskCallback`, `taskCallbackManager`\ http://developer.r-project.org/TaskHandlers.pdf

### Examples

     n <- addTaskCallback(function(expr, value, ok, visible) {
                            cat("In handler\n")
                            return(TRUE)
                          }, name = "simpleHandler")

     getTaskCallbackNames()

       # now remove it by name
     removeTaskCallback("simpleHandler")

     h <- taskCallbackManager()
     h$add(function(expr, value, ok, visible) {
                            cat("In handler\n")
                            return(TRUE)
                          }, name = "simpleHandler")
     getTaskCallbackNames()
     removeTaskCallback("R-taskCallbackManager")

[Package base version 2.6.2 Index]