check.options           package:grDevices           R Documentation

Set Options with Consistency Checks

Description:

     Utility function for setting options with some consistency checks.
     The 'attributes' of the new settings in 'new' are checked for
     consistency with the _model_ (often default) list in 'name.opt'.

Usage:

     check.options(new, name.opt, reset = FALSE, assign.opt = FALSE,
                   envir = .GlobalEnv,
                   check.attributes = c("mode", "length"),
                   override.check = FALSE)

Arguments:

     new: a _named_ list

name.opt: character with the name of R object containing the default
          list.

   reset: logical; if 'TRUE', reset the options from 'name.opt'.  If
          there is more than one R object with name 'name.opt', remove
          the first one in the 'search()' path.

assign.opt: logical; if 'TRUE', assign the ...

   envir: the 'environment' used for 'get' and 'assign'.

check.attributes: character containing the attributes which
          'check.options' should check.

override.check: logical vector of length 'length(new)' (or 1 which
          entails recycling). For those 'new[i]' where
          'override.check[i] == TRUE', the checks are overridden and
          the changes made anyway.

Value:

     A list of components with the same names as the one called
     'name.opt'. The values of the components are changed from the
     'new' list, as long as these pass the checks (when these are not
     overridden according to 'override.check').

Note:

     Option '"names"' is exempt from all the checks or warnings, as in
     the application it can be 'NULL' or a variable-length character
     vector.

Author(s):

     Martin Maechler

See Also:

     'ps.options' and 'pdf.options', which use 'check.options'.

Examples:

     (L1 <- list(a=1:3, b=pi, ch="CH"))
     check.options(list(a=0:2), name.opt = "L1")
     check.options(NULL, reset = TRUE, name.opt = "L1")

