Gerbil Scheme

Multicall Binaries

The :std/cli/multicall module provides facilities to define multicall binaries the behavior of which differs depending on the name of the binary, just like the gerbil binary itself, or famously like busybox.

usage

(import :std/cli/multicall)

An earlier version of this library used to be available as :clan/multicall in gerbil-utils.

Interface

current-program

(def current-program (make-parameter []))

A parameter that contains the name of the current program or subprogram, as a list in reverse of the successive subcommands used to invoke it.

current-program-string

(def current-program (make-parameter []))

Return as a string of space-separated commands and subcommands in order the name of the current program or subprogram.

entry-points

entry-points => table

A table, indexed by symbols, of entry-point structs, describing the available shell entry points.

entry-point

(defstruct entry-point (name function help getopt) transparent: #t)

A struct type describing an available entry-point:

  • name is a symbol, whose symbol->string is used as command or subcommand to select the entry-point from the CLI.
  • function is the Scheme function to call if the entry-point is selected.
  • help is a short help string describing the purpose of the entry-point, to be displayed to the user when help is requested.
  • getopt is a getopt-spec based on which the rest of the command-line will be parsed, and based on which help about the available options is displayed.

entry-points-getopt-spec

(entry-points-getopt-spec [table])

Given a table of entry-points which default to the variable entry-points, return a getopt-spec (suitable to be passed to (apply getopt ...)) of command specifiers, one for each registered entry-point, in asciibetical order.

register-entry-point

(register-entry-point function
  [id: #f] [name: #f] [help: #f] [getopt: #f])

Register the function as entry-point, with given name (argument passed to make-symbol), or if not specified, a symbol made of only the easy-shell-characters? of id. The entry-point will have the given help and getopt fields.

define-entry-point

(define-entry-point (id . formals) (options ...) body ...)

Syntax that expands to both

  1. defining in the current scope function with the given name id and specified Scheme function formals, and the given body.
  2. register an entry-point for that function, with given id and options.

multicall-default

multicall-default

A mutable variable that contains the default function to call if the command doesn’t match any of the specified commands.

set-default-entry-point!

(set-default-entry-point! symbol)

Set the default entry-point in multicall-default as given symbol.

help

(help [command])

Global entry-point to print a help message (about the command, if specified) about the current overall command and subcommands.

meta

(meta)

Global entry-point to print the available completions for the command, for use with CLI syntax autodetection.

version

(version [all?: #f] [layer])

Global entry-point to print the current version. If all? (flag -a) is passed, print all components from build manifest. If layer (flag -l) is passed, print the thus-named component.

call-entry-point

(call-entry-point . args)

Call an entry point as specified by args, or else the multicall-default entry point.

define-multicall-main

define-multicall-main

Define call-entry-point as a suitable main function in the current scope.

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