evaluatorActions {XR}

Add to Table of Search Paths and Import Commands

Description

Utilities to add to the table of search paths, import commands and tasks for all evalutors of the specified class. Called only from analogous functions in packages for specific languages.

Usage

serverAddToPath(Class, directory,
  package = utils::packageName(topenv(parent.frame())), pos = NA,
  onLoad = NA, where = topenv(parent.frame()))

serverImport(Class, ..., onLoad = nzchar(packageName(where))  &&
                 !environmentIsLocked(where),  where = topenv(parent.frame()))

serverTask(Class, command, onLoad = nzchar(packageName(where)),
  where = topenv(parent.frame()))

Arguments

Class

the class of the server-specific evalutor.

directory

the directory to add to the search path table.

package

the name of the server-specific interface package.

pos

where in the list of directories to insert this one. Defaults to the end.

onLoad, where

used to set up a load action; should be omitted if called from a package source

...

arguments to pass to the evaluator's $Import() method

command

an unevaluated command or expression for the evaluator.

Details

The server-specific information is added to the table stored by the XR package. All future evaluators for the specified interface class will have these directories in their search path, will import the module information specified and carry out any other tasks supplied.

If a current evaluator for this class exists, it applies all the commands, but previous evalutors for this class are not modified.

Commands are evaluated in the order of the calls to these functions. For example, the application package should execute a call to add to the search path before any calls to import modules form the corresponding directory.

Functions

• serverAddToPath: Add the directory to the search path of all evaluators of this class.

• serverImport: An import command with these arguments will be executed for each new evaluator of this interface class, and for the current evaluator if one exists.

• serverTask: An unevalated command or expression for the interface is supplied, typically using quote() or substitute. When an evaluator from the class is created, this command will be evaluated.

References

Chambers, John M. (2016) Extending R, Chapman & Hall/CRC. ( Chapter 13, discussing this package, is included in the package: ../doc/Chapter_XR.pdf.)