base-internal              package:base              R Documentation

Internal Functions in the Base Package

Description:

     Internal functions in the base package, which are only
     user-visible because of the special nature of the base name space.

Usage:

     .subset(x, ...)
     .subset2(x, ...)

     .find.package(package, lib.loc = NULL, quiet = FALSE,
                   verbose = getOption("verbose"))

     .path.package(package, quiet = FALSE)

     .getRequiredPackages(file = "DESCRIPTION", quietly = FALSE,
                          useImports = FALSE)
     .getRequiredPackages2(pkgInfo, quietly = FALSE, lib.loc = NULL,
                           useImports = FALSE)

     testPlatformEquivalence(built, run)

     .isMethodsDispatchOn(onOff = NULL)

     sys.load.image(name, quiet)
     sys.save.image(name)

     .row_names_info(x, type = 1L)
     .set_row_names(n)

     findPackageEnv(info)

     lazyLoadDBfetch(key, file, compressed, hook)

     .TAOCP1997init(seed)

Arguments:

       x: object from which to extract elements.

 package: the name of a package.

 lib.loc: a character vector describing the location of R library trees
          to search through, or 'NULL'.  The default value of 'NULL'
          corresponds to all libraries currently known.

   quiet: logical.  Should this not give warnings or an error if the
          package(s) are not found?

useImports: logical.  Should  the 'Imports' field be processed?

 verbose: a logical.  If 'TRUE', additional diagnostics are printed.

    file: The full path to the 'DESCRIPTION' file of a package.

 quietly: logical: should message(s) be printed.

 pkginfo: A processed 'DESCRIPTION' file of class
          '"packageDescription2"'.

built, run: platform strings of the form '"cpu-vendor-os"'.

    name: name of image file to save or load.

       x: an object with a '"row.names"' attribute, typically a data
          frame.

    type: integer. Currently 'type = 0' returns the internal
          '"row.names"' attribute (possibly 'NULL'), 'type = 2' the
          number of rows implied by the attribute, and 'type = 1' the
          latter with a negative sign for 'automatic' row names.

       n: integer.  The number of rows.

    info: character string such as '"package:MASS"'.

     key: the object name in a lazyload database.

    file: the filepath to a lazyload database.

compressed: logical: are the values in the database compressed?

 refhook: a load hook: see 'unserialize'.

    seed: a length-one integer vector.

Details:

     The functions '.subset' and '.subset2' are essentially equivalent
     to the '[' and '[[' operators, except that methods dispatch does
     not take place.  This is to avoid expensive unclassing when
     applying the default method to an object.  They should not
     normally be invoked by end users.  Note that unlike the operators
     they are builtins and not specials (all arguments are evaluated)
     and hence do not allow missing arguments.

     '.find.package' returns the paths to the locations where the given
     packages can be found.  If 'lib.loc' is 'NULL', then then attached
     packages are searched before the libraries.  If a package is found
     more than once, the first match is used.  Unless 'quiet = TRUE' a
     warning will be given about the named packages which are not
     found, and an error if none are.  If 'verbose' is true, warnings
     about packages found more than once are given.  It does know about
     versioned installs of packages, and for a package to be returned
     it must have a 'DESCRIPTION' file containing a valid 'version'
     field.  Where more than one versioned match is found to a
     unversioned name (and no exact match), the highest-numbered
     version is selected.

     '.path.package' returns the paths from which the named packages
     were loaded, or if none were named, for all currently loaded
     packages. Unless 'quiet = TRUE' it will warn if some of the
     packages named are not loaded, and given an error if none are. 
     This function is not meant to be called by users, and its
     interface might change in future versions.  Note that currently
     'package' must include the version number if versioned installs
     are used.

     '.getRequiredPackages2' attaches all the packages mentioned in the
     'Depends' field: failure to find a package is an error.  It also
     checks the versions of the packages found against the 'Depends'
     field.

     '.getRequiredPackages' is a wrapper to '.getRequiredPackages2'
     using a 'DESCRIPTION' file.

     'testPlatformEquivalence' is used to test if a package with 
     compiled code can safely be loaded into a build of R, which it
     does by comparing their 'canonical' '"cpu-vendor-os"'
     descriptions. The default function omits the 'vendor' part and
     allows small  mismatches elsewhere.  Cognoscenti can replace this
     function in the 'base' name space.

     The function '.isMethodsDispatchOn()' returns 'TRUE' if the S4
     method dispatch has been turned on in the evaluator (usually by
     loading package 'methods').  It is meant for R internal use only.

     'sys.save.image' is a system function that is called by 'q()' and
     its GUI analogs; 'sys.load.image' is called by the startup code.
     These functions should not be called directly and are subject to
     change.

     'sys.save.image' closes all connections first, to ensure that it
     is able to open a connection to save the image.  This is
     appropriate when called from 'q()' and allies, but reinforces the
     warning that it should not be called directly.

     'row.names' can be stored internally in compact form.
     '.set_row_names(n)' generates that form for automatic row names of
     length 'n', to be assigned to 'attr(<a data frame>, "row.names")'.
      '.row_names_info' gives information on the internal form of the
     row names for a data frame: for details of what information see
     the argument 'type'.

     '.GenericArgsEnv' and '.ArgsEnv' are environments that contain
     closures with the argument lists that the primitives would have
     had had they been closures.  All the primitives that are internal
     S3 generics have corresponding members of '.GenericArgsEnv' and
     the remaining non-language-element primitives correspond to
     '.ArgsEnv'. See the 'R Internals' manual for further details. 
     They are used by 'args' and 'print.default' and the QC functions
     'codoc' and 'checkS3methods'.

     'findPackageEnv' is invoked by the unserialize code to set a saved
     environment if possible.

     '.TAOCP1997init' is the initialization code for the
     '"Knuth-TAOCP"' RNG.

Value:

     '.find.package' and '.path.packages' return a character vector of
     paths to installed packages.

     '.getRequiredPackages' and '.getRequiredPackages2' return
     'invisible()'.

     'testPlatformEquivalence': 'TRUE' or 'FALSE'.

