Using clap on wasm

[cBournhonesque]

Hi,

Apologies if this is a stupid question. How can I use clap over wasm?
I have target = wasm32-unknown-unknown and

[target.wasm32-unknown-unknown]
runner = "wasm-server-runner"

I launch my app with cargo run --target wasm32-unknown-unknown -- client -c 1 (the arguments at the end should be parsed by clap), but i'm getting:

wasm.wasm:0x4d8f59e Uncaught (in promise) RuntimeError: unreachable
    at std::process::exit::hff913a499bc43a8e (wasm.wasm:0x4d8f59e)
    at clap_builder::util::safe_exit::h796b9ff5c7d45f5b (wasm.wasm:0x3602457)
    at clap_builder::error::Error<F>::exit::hd46885ebbd305bcc (wasm.wasm:0x478220a)
    at clap_builder::builder::command::Command::get_matches_from::{{closure}}::h501d2a20f108e1c6 (wasm.wasm:0x473356b)
    at core::result::Result<T,E>::unwrap_or_else::h3246409be3a31f30 (wasm.wasm:0x272b089)
    at clap_builder::builder::command::Command::get_matches_from::h688a6a7c3b2a78a3 (wasm.wasm:0x4140e43)
    at clap_builder::builder::command::Command::get_matches::he70ca48415cf1dfa (wasm.wasm:0x4d89172)
    at clap_builder::derive::Parser::parse::hdf9047aead4594a0 (wasm.wasm:0x32147bf)
    at interest_management::main::h769560f173875df4 (wasm.wasm:0x383af72)
    at core::ops::function::FnOnce::call_once::h7e2d1bed71cc0024 (wasm.wasm:0x4bb7254)

I couldn't figure out after some googling what I am supposed to do

[epage]

I've never used it with wasm personally so its hard to say.

Just judging from that call stack, it looks like a call to std::process:exit caused an exception. If that doesn't work for you, you could instead use Parser::try_parse and deal with the error as works best for you.

[cBournhonesque]

I tried printing the error in the console, it looks like my CLI arguments are not getting recognized. The full error is

failed to parse cli: ErrorInner { kind: DisplayHelpOnMissingArgumentOrSubcommand, context: FlatMap { keys: [], values: [] }, message: Some(Formatted(StyledStr("\u{1b}[1m\u{1b}[4mUsage:\u{1b}[0m \u{1b}[1mlightyear_examples\u{1b}[0m <COMMAND>\n\n\u{1b}[1m\u{1b}[4mCommands:\u{1b}[0m\n  \u{1b}[1msingle-player\u{1b}[0m  \n  \u{1b}[1mclient\u{1b}[0m         \n  \u{1b}[1mhelp\u{1b}[0m           Print this message or the help of the given subcommand(s)\n\n\u{1b}[1m\u{1b}[4mOptions:\u{1b}[0m\n  \u{1b}[1m-h\u{1b}[0m, \u{1b}[1m--help\u{1b}[0m  Print help\n"))), source: None, help_flag: Some("--help"), styles: Styles { header: Style { fg: None, bg: None, underline: None, effects: Effects(BOLD | UNDERLINE) }, error: Style { fg: Some(Ansi(Red)), bg: None, underline: None, effects: Effects(BOLD) }, usage: Style { fg: None, bg: None, underline: None, effects: Effects(BOLD | UNDERLINE) }, literal: Style { fg: None, bg: None, underline: None, effects: Effects(BOLD) }, placeholder: Style { fg: None, bg: None, underline: None, effects: Effects() }, valid: Style { fg: Some(Ansi(Green)), bg: None, underline: None, effects: Effects() }, invalid: Style { fg: Some(Ansi(Yellow)), bg: None, underline: None, effects: Effects() } }, color_when: Auto, color_help_when: Auto, backtrace: None }

[stonerfish]

The runner you are using, wasm-server-runner does not provide env.args().
So clap has nothing to parse().
Then also the runner does not provide process.exit() so claps safe_exit() fails.

There is a workaround I am working on.
When running on web, I use the web url. I use the query string as the args. It works, but I have npt figured out what to do at the point of error you hit. What do I call in wasm instead of process::exit() to stop the execution?

Also the stdoout / stderr issues. Putting the text to log instead of stdout / stderr. But that is just details.

[stonerfish]

pendant mode<
The rust std for wasm has a very simple

pub fn args() -> Args {
    Args {}
}

so it isn't your framework not giving you args, it is the compiler. wasi target has args "sometimes" depending on the runner.

[cBournhonesque]

So what do you think would be the best solution for easily provide CLI args in wasm?

[stonerfish]

If you are still around...
I made a library to wrap clap so your programs can run native or on web browser such as with wasm_server_runner and still have clap's awesome powers.
I call it we_clap
It parses the args from the url when on the web. If you don't mind, give it a try and if you need help figuring out how, just ask.