debug

[dvv]

Hi!

How do I pass node executable options when running a coffee script with coffee binary or simply running a chmod a+x file with #!/usr/bin/env coffee?

In particular, I want to pass --debug-brk

TIA,
--Vladimir

[michaelficarra]

I believe you put -- after your coffee arguments and before your node arguments, but I have no way of testing it right now. -- usually signifies the end of a parameter list. Try that out and let me know if it worked for you.

[dvv]

Hmmm.

coffee --debug-brk script.coffee barks

Error: unrecognized option: --debug-brk
at OptionParser.parse (/home/dvv/NODE/coffee-script/lib/optparse.js:29:17)

coffee -- --debug-brk script.coffee simply does nothing

[michaelficarra]

What I was trying to convey was coffee script.coffee -- --debug. All the regular coffeescript arguments followed by -- followed by all of your node arguments.

[dvv]

script gets executed but options don't get honored.

Feasible would be to pass any options which coffee doesn't recognize to the node intact

[jashkenas]

I'm afraid that there isn't a way to pass arguments directly to the node interpreter from the coffee command ... because by the time that the coffee command has started running, Node has already been invoked. The complete source code for coffee is available here:

https://github.com/jashkenas/coffee-script/blob/master/bin/coffee

[michaelficarra]

I was going to write a nice, detailed message, but I'm lazy so I will just paste the related section of IRC chat:

• <michaelficarra> Regarding vladimir's problem with not being able to pass arguments to node: I don't see why we can't
• <michaelficarra> I know node is already running coffee, but can't we just execve or something similar and change the process to a new node instance with the given arguments?
• <jashkenas> Sure, we could do that.
• <michaelficarra> I'm not too familiar with node's process management capabilities, but it must have something like that
• <jashkenas> We'd have to keep a list of all valid Node arguments.
• <jashkenas> It'd be a bit ugly.
• <jashkenas> Why not just compile the code and run it with Node?
• <michaelficarra> why? just pass everything after -- to node
• <michaelficarra> if node doesn't recognize it, it will give an appropriate error
• <jashkenas> Things after -- are already for passing options to your own scripts.
• <michaelficarra> ah, I see
• <jashkenas> --help is CoffeeScript's help ... unless you pass it after --.
• <michaelficarra> then it's your own script's argument, not node's
• <jashkenas> right.
• <michaelficarra> I guess we could just allow a --node argument that accepts a list of node arguments as a string
• <jashkenas> and then exec...
• <michaelficarra> for example: coffee --node "--debug --something-else" script.coffee
• <michaelficarra> yeah
• <michaelficarra> it wouldn't be the most elegant solution, but it wouldn't be a hack either
• <jashkenas> sure.
• <jashkenas> I'll reopen the ticket.
• <michaelficarra> And I'll make a note about how I was mistaken about coffee's behaviour when given -- and describe its actual purpose

[dvv]

Excellent. Also an environment variable can hold node options

[dvv]

This is how a "fork" can be made in node. Hope this helps

#!/usr/bin/env node

if (process.env.coffeenodeargs) {
var args = process.argv.slice(1);
args.unshift(process.env.coffeenodeargs);
delete process.env.coffeenodeargs;
console.log('SPAWN');
console.log('ARGS:', args);
require('child_process').spawn(process.argv[0], args, process.env, [0,1,2]);
console.log('SPAWNED');
} else {
console.log('CHILD NODE');
// main script here
}

[michaelficarra]

I don't think a child process is the way to go with this. I see that you're passing the custom file descriptors to redirect stdin, stdout, and stderr, but is there no way to actually replace the current process with a new process (see man execl)?

[dvv]

I thought we'd want to stay in node infrastructure. There's no exec (in syscall sense) in node which i'm aware of.

If we could make coffee binary a shell script, things would be done easier.

[michaelficarra]

We do want to stay within node, I was just hoping they would have something comparable. Though after looking for a while, it seems that spawning the child process may be our best bet.

[dvv]

Right. And passing [0,1,2] as descriptors just delegates parent's channels to the child, so coffeenodeargs='--debug' coffee !.coffee >1 2>2 <3 should work as expected

[dvv]

$ node --debug /usr/local/bin/coffee index.coffee is the solution w/o touching anything. Think we can close the issue. Thanks to all participants.

--Vladimir

[michaelficarra]

@dvv: I still plan on adding the --node flag for passing through node arguments. Nice temporary fix, though.

[dvv]

Staying tuned,
--Vladimir

[michaelficarra]

@dvv: this is now fixed on a branch in my fork, waiting on pull request 945.