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---
title: .NET AOT 下的 F# 命令行参数解析库选择
date: 2024-06-06 20:50:35
tags: [Technique]
---
Argu 不支持 AOT，不过用 F# 的话可以看整个 .NET 的生态，我看了一下 C# 的 CommandLineParser：
https://github.com/commandlineparser
在这个 PR 中支持了 Native AOT
https://github.com/commandlineparser/commandline/pull/913
除此之外，还有一个更加精巧的 F# 库可以用，只有两百多行：
https://github.com/B2R2-org/FsOptParse/
AOT 后的大小很可观，并且支持 full trim.
用例：
```fsharp
(** defines a state to pass to the option parser *)
type opts =
{
optX : int;
optY : bool;
optZ : string;
}
(** default option state *)
let defaultOpts =
{
optX = 0;
optY = false;
optZ = "";
}
(*
An example command line specification, which is a list of Options.
Each Option describes a command line option (switch) that is specified with
either a short (a single-dash option) or long option (a double-dash option).
*)
let spec =
[
(* This option can be specified with -x <NUM>. There is an extra argument to
specify a value in integer. *)
Option ((* description of the option *)
descr="this is a testing param X",
(* how many extra argument must be provided by a user? *)
extra=1,
(* callback sets up the option and returns it *)
callback=(fun opts arg -> {opts with optX=(int) arg.[0]}),
(* use a short option style -x *)
short="-x"
);
(* This option can be specified with -y. There is no extra argument. This
option just sets a flag, optY. *)
Option ((* description of the option *)
descr="this is a testing param Y",
(* set the option to be true *)
callback=(fun opts _ -> {opts with optY=true}),
(* use a short option style (-y) *)
short="-y",
(* also use a long option style (--yoohoo) *)
long="--yoohoo"
);
(* A dummy option to pretty-print the usage *)
Option ((* description of the option *)
descr="",
dummy=true
);
Option ((* description of the option *)
descr="[Required Options]",
descrColor=System.ConsoleColor.DarkCyan,
dummy=true
);
(* The third option is a required option. In other words, option parsing
will raise an exception if this option is not given by a user. This
option takes in an additional integer argument, and set it to the global
variable z. *)
Option ((* description of the option *)
descr="required parameter <STRING> with an integer option",
(* callback to set the optZ value *)
callback=(fun opts arg -> {opts with optZ=arg.[0]}),
(* specifying this is a required option *)
required=true,
(* one additional argument to specify an integer value *)
extra=1,
(* use only a long option style *)
long="--req"
);
]
let _ =
let prog = "opttest.fsx"
let args = System.Environment.GetCommandLineArgs ()
let usageGetter () = "[Usage]\n %p %o"
try
let left, opts = optParse spec usageGetter prog args defaultOpts
printfn "Rest args: %A, x: %d, y: %b, z: %s"
left opts.optX opts.optY opts.optZ
0
with
| SpecErr msg ->
eprintfn "Invalid spec: %s" msg
exit 1
| RuntimeErr msg ->
eprintfn "Invalid args given by user: %s" msg
usagePrint spec prog usageGetter (fun () -> exit 1)
```
|
