116 lines
4.3 KiB
Racket
116 lines
4.3 KiB
Racket
#lang scribble/doc
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@(require scribble/manual
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"common.ss"
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(for-label racket/base
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raco/command-name
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racket/cmdline))
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@title[#:tag "command"]{Adding a @exec{raco} Command}
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The set of commands supported by @exec{raco} can be extended by
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installed collections and @|PLaneT| packages. A command is added by
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defining @indexed-racket[raco-commands] in the @filepath{info.rkt}
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library of a collection or package (see @secref["info.rkt"]).
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The value bound to @racket[raco-commands] must be a list of command
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specifications, where each specification is a list of four values:
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@schemeblock[
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(list _command-string
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_implementationmodule-path
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_description-string
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_prominence)
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]
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The @racket[_command-string] is the command name. Any unambiguous
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prefix of a command name can be supplied to @exec{raco} to invoke the
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command.
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The @racket[_module-path] names the implementation though a module
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path (in the sense of @scheme[module-path?]). The module is loaded and
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invoked through @racket[dynamic-require] to run the command. The
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module can access command-line arguments through the
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@racket[current-command-line-arguments] parameter, which is adjusted
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before loading the command module to include only the arguments to the
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command. The @racket[current-command-name] parameter is also set to
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the command name used to load the command. When @exec{raco help} is
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used on a command, the command is launched with an initial
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@DFlag{help} argument in @racket[current-command-line-arguments].
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The @racket[description] string is a short string used to describe the
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command in response to @exec{raco help}. The description should not be
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capitalized or end with a period.
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The @racket[_prominence] value should be a read number or
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@scheme[#f]. A @racket[#f] value means that the command should not be
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included in the short list of ``frequently used commands.'' A number
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indicates the relative prominence of the command; the @exec{help}
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command has a value of @racket[110], and probably no command should be
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more prominent. The @exec{pack} tool, which is currently ranked as the
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least-prominent of the frequently used commands, has a value of
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@racket[10].
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As an example, the @filepath{info.rkt} of the "compiler" collection
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might contain the
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@schemeblock[
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(define raco-commands
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'(("make" compiler/commands/make "compile source to bytecode" 100)
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("decompile" compiler/commands/decompile "decompile bytecode" #f)))
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]
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so that @exec{make} is treated as a frequently used command, while
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@exec{decompile} is available as an infrequently used command.
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@section{Command Argument Parsing}
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@defmodule[raco/command-name]{The @racketmodname[raco/command-name]
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library provides functions to help a @exec{raco} command identify
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itself to users.}
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@defparam[current-command-name name (or/c string? #f)]{
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The name of the command currently being loaded via
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@racket[dynamic-require], or @racket[#f] if @exec{raco} is not loading
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any command.
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A command implementation can use this parameter to determine whether
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it was invoked via @exec{raco} or through some other means.}
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@defproc[(short-program+command-name) string?]{
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Returns a string that identifies the current command. When
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@racket[current-command-name] is a string, then the result is the
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short name of the @exec{raco} executable followed by a space and the
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command name. Otherwise, it is the short name of the current
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executable, as determined by stripping the path from the result of
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@racket[(find-system-path 'run-file)].
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The result of this function is suitable for use with
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@racket[command-line]. For example, the @exec{decompile} tool parses
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command-line arguments with
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@schemeblock[
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(define source-files
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(command-line
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#:program (short-program+command-name)
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#:args source-or-bytecode-file
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source-or-bytecode-file))
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]
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so that @exec{raco decompile --help} prints
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@verbatim[#:indent 2]{
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raco decompile [ <option> ... ] [<source-or-bytecode-file>] ...
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where <option> is one of
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--help, -h : Show this help
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-- : Do not treat any remaining argument as a switch (at this level)
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Multiple single-letter switches can be combined after one `-'; for
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example: `-h-' is the same as `-h --'
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}}
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@defproc[(program+command-name) string?]{
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Like @racket[short-program+command-name], but the path (if any) is not
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stripped from the current executable's name.}
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