base-internal              package:base              R Documentation

_I_n_t_e_r_n_a_l _F_u_n_c_t_i_o_n_s _i_n _t_h_e _B_a_s_e _P_a_c_k_a_g_e

_D_e_s_c_r_i_p_t_i_o_n:

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

_U_s_a_g_e:

     .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)

_A_r_g_u_m_e_n_t_s:

       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 progress messages be given.

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

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

_D_e_t_a_i_l_s:

     The functions '.subset' and '.subset2' are essentially equivalent
     to the '[' and '[[' operators, except methods that 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.

     '.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.

     '.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 mumber 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.  Cognescenti can replace this
     function in the 'base' namespace.

_V_a_l_u_e:

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

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

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

