opt_get_verb: Get verb from the command line

In optigrab: Command-Line Parsing for an R World

Description

Return the verb for the application. The verb is the first argument that is not part of an option.

Usage

opt_get_verb(opts = commandArgs())

Arguments

opts	character; Vector from which to parse options (default: commandArgs() )

Details

Some applications such as git support command verbs, e.g. push, fetch, etc. These style arguments can be retrieved by opt_get_verb.

opt_get_verb look for the first unaccounted for options (after --args). The number of options needed by each flags is determined by and saved by calls to opt_get(). See the details to see how n is automatically determined. When not explicitly defined the number of options needed by each flag is 1. Becasue of this, it convention to call opt_get_verb after all opt_get calls. For most simple applications, it likely doesn't matter.

Value

character of length 1; the verb found from the command-line. NA if a verb cannot be identified.

Assumptions

opt_get_verb assumes any flags occurring before the verb have exactly 1 value. A command line such as "> myscript –verbose verb" will be misparsed; the code will assume that "verb" is the value of the flag "–verbose"

See Also

• opt_get()

• base::commandArgs()

Examples

  opt_get_verb()  # commandArgs()
  

Example output

[1] "/usr/lib/R/bin/exec/R"

optigrab documentation built on May 2, 2019, 2:10 a.m.