▼raco: Racket Command-Line Tools
►9 Adding a raco Command
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9.1 Command Argument Parsing
current-command-name
short-program+ command-name
program+ command-name
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9 Adding a raco Command

The set of commands supported by raco can be extended by installed collections and PLaneT packages. A command is added by defining raco-commands in the "info.rkt" library of a collection or package (see "info.rkt" File Format).

The value bound to raco-commands must be a list of command specifications, where each specification is a list of four values:

  (list command-string
        implementationmodule-path
        description-string
        prominence)

The command-string is the command name. Any unambiguous prefix of a command name can be supplied to raco to invoke the command.

The module-path names the implementation though a module path (in the sense of module-path?). The module is loaded and invoked through dynamic-require to run the command. The module can access command-line arguments through the current-command-line-arguments parameter, which is adjusted before loading the command module to include only the arguments to the command. The current-command-name parameter is also set to the command name used to load the command. When raco help is used on a command, the command is launched with an initial --help argument in current-command-line-arguments.

The description string is a short string used to describe the command in response to raco help. The description should not be capitalized or end with a period.

The prominence value should be a read number or #f. A #f value means that the command should not be included in the short list of “frequently used commands.” A number indicates the relative prominence of the command; the help command has a value of 110, and probably no command should be more prominent. The pack tool, which is currently ranked as the least-prominent of the frequently used commands, has a value of 10.

As an example, the "info.rkt" of the "compiler" collection might contain the

  (define raco-commands
    '(("make" compiler/commands/make "compile source to bytecode" 100)
      ("decompile" compiler/commands/decompile "decompile bytecode" #f)))

so that make is treated as a frequently used command, while decompile is available as an infrequently used command.

9.1 Command Argument Parsing

 (require raco/command-name)
The raco/command-name library provides functions to help a raco command identify itself to users.

(current-command-name) → (or/c string? #f)
(current-command-name name) → void?
  name : (or/c string? #f)
The name of the command currently being loaded via dynamic-require, or #f if raco is not loading any command.

A command implementation can use this parameter to determine whether it was invoked via raco or through some other means.

(short-program+command-name) → string?
Returns a string that identifies the current command. When current-command-name is a string, then the result is the short name of the raco executable followed by a space and the command name. Otherwise, it is the short name of the current executable, as determined by stripping the path from the result of (find-system-path 'run-file).

The result of this function is suitable for use with command-line. For example, the decompile tool parses command-line arguments with

  (define source-files
    (command-line
     #:program (short-program+command-name)
     #:args source-or-bytecode-file
     source-or-bytecode-file))

so that raco decompile --help prints

  raco decompile [ <option> ... ] [<source-or-bytecode-file>] ...

  where <option> is one of

   --help, -h : Show this help

   -- : Do not treat any remaining argument as a switch (at this level)

  Multiple single-letter switches can be combined after one `-'; for

   example: `-h-' is the same as `-h --'

(program+command-name) → string?
Like short-program+command-name, but the path (if any) is not stripped from the current executable’s name.

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