get_help_file: Retrieve an Rd object of a help query

Description

Safely return NULL if an error is encountered.

Usage

get_help_file(...)

Arguments

...

Arguments passed on to utils::help

topic

usually, a name or character string specifying the topic for which help is sought. A character string (enclosed in explicit single or double quotes) is always taken as naming a topic.

If the value of topic is a length-one character vector the topic is taken to be the value of the only element. Otherwise topic must be a name or a reserved word (if syntactically valid) or character string.

See ‘Details’ for what happens if this is omitted.

package

a name or character vector giving the packages to look into for documentation, or NULL. By default, all packages whose namespaces are loaded are used. To avoid a name being deparsed use e.g. (pkg_ref) (see the examples).

lib.loc

a character vector of directory names of R libraries, or NULL. The default value of NULL corresponds to all libraries currently known. If the default is used, the loaded packages are searched before the libraries. This is not used for HTML help (see ‘Details’).

verbose

logical; if TRUE, the file name is reported.

try.all.packages

logical; see Note.

help_type

character string: the type of help required. Possible values are "text", "html" and "pdf". Case is ignored, and partial matching is allowed.

Value

the Rd object returned from utils:::.getHelpFile