test.rs

#[macro_use]
extern crate serenity;

#[macro_use]
extern crate structopt;

use structopt::StructOpt;

use std::{collections::HashMap, env, fmt::Write, sync::Arc};

use serenity::{
    client::bridge::gateway::{ShardId, ShardManager},
    framework::standard::{
        help_commands, Args, CommandOptions, DispatchError, HelpBehaviour, StandardFramework,
    },
    model::{channel::Message, gateway::Ready, Permissions},
    prelude::*,
    utils::{content_safe, ContentSafeOptions},
};

use serenity::framework::standard::Command;
use serenity::framework::standard::CommandError;

// This imports `typemap`'s `Key` as `TypeMapKey`.
use serenity::prelude::*;


struct Handler;

impl EventHandler for Handler {
    fn ready(&self, _: Context, ready: Ready) {
        println!("{} is connected!", ready.user.name);
    }
}

fn main() {
    // Configure the client with your Discord bot token in the environment.
    let token = env::var("DISCORD_TOKEN").expect(
        "Expected a token in the environment",
    );
    let mut client = Client::new(&token, Handler).expect("Err creating client");

    client.with_framework(
        StandardFramework::new()
        .configure(|c| c
            .allow_whitespace(true)
            .on_mention(true)
            .prefix(".")
            .delimiters(vec![", ", ","]))
        .command("ping", |c| c
            .cmd(ping))
    );

    if let Err(why) = client.start() {
        println!("Client error: {:?}", why);
    }
}

#[derive(StructOpt, PartialEq, Debug)]
struct Opt {
    #[structopt(short = "a", long = "arg")]
    arg: i32,
}

struct ping;

impl Command for ping {
    fn execute(&self, ctx: &mut Context, msg: &Message, args: Args) -> Result<(), CommandError> {
        let original = msg.content.split_whitespace();
        
        let options = Opt::from_iter_safe(original).unwrap_or(Opt { arg : 0 }); // Error handling here
        if let Err(why) = msg.channel_id.say(format!("Pong! : ) ({})", options.arg)) {
            println!("Error sending message: {:?}", why);
        }
        Ok(())
    }
}