New option parser: which flags must live?

[Chris Leary]

[Cross posted from moz-dev-tech-js-engine-internals]

A few folks told me that it would be useful to have a proper option
parser for JS going forward, so I made the patch in bug 668095.

I'd like to know which options people actually use, so I can just drop
the other ones. Right now, this is the help text in debug mode (which
automatically formats itself when you add new options -- yay!):

"""
Usage: ./js [options]

The SpiderMonkey shell provides a command line interface to the
JavaScript engine. Code and file options provided via the command
line are run left to right. Just-In-Time compilation modes may be
enabled via command line options.

Version: JavaScript-C 1.8.5+ 2011-04-16

Options:
-f --file=PATH File path to run
-e --execute=CODE Inline code to run
-i --repl Enter prompt after running code
-m --methodjit Enable the JaegerMonkey method JIT
-j --tracejit Enable the JaegerMonkey trace JIT
-p --profiling Enable runtime profiling select JIT mode
-n --type-infer Run the type inferencing engine
-d --debugjit Enable runtime debug mode for method JIT code
-a --always-mjit Do not try to run in the interpreter before
method
jitting. Note that this has no particular
effect on
the tracer; it still kicks in if enabled.
-b --print-timing Print sub-millisecond runtime for each file
that's
run
-A --oom-after=COUNT Trigger OOM after COUNT allocations
-O --print-alloc Print the number of allocations at exit
-Z --gc-zeal=N[,F[,C]] N indicates "zealousness":
0: no additional GCs
1: additional GCs at common danger points
2: GC every F allocations (default: 100)
If C is 1, compartmental GCs are performed;
otherwise, full
-U --utf8 C strings passed to the JSAPI are UTF-8 encoded
"""

Let me know if any useful ones are missing.

- Leary

[gavrilyak]

>Let me know if any useful ones are missing.

From bug 668095

>Note that we no longer bind an arguments array on the global object.

Arguments was useful. Any plans to bring them back in some form?

Thanks,
Vassily

[Chris Leary]

On 07/13/2011 11:54 AM, gavrilyak wrote:
> Arguments was useful. Any plans to bring them back in some form?

I'd love to discuss how best to add it back; although, I'd like to give
it a different identifier binding in the global scope, at least. Would
you mind describing your use case in more detail?

Thanks!

- Leary

[Joshua Cranmer]

I have used arguments to run xpcshell files as scripts, e.g., switching
ports as an option, or telling which script needs to bind port listeners.

[gavrilyak]

My use cases are usual (int argc, char **argv), e.g. specify some
options
for script, like port number, files to process, etc.
JS shell supports #!/usr/bin/js , so I just "chmod a+x script.js" and
run it
from command line, same way as with bash or python or whatever. One
thing I am currently missing is the script name (like argv[0]), but
that's not
very important. Actually, I can live without arguments at all, (/proc/
cmdline),
but that's not portable.

I agree that different identifier makes sense, "arguments" are special
in JS,
and having them in global scope is probably not the best way to do
it.
But I have no ideas for better identifier, "arguments" are just that -
arguments
to script, so I just imagine that script itself is a function.

Thanks for asking,

Vassily

[Chris Leary]

On 07/14/2011 02:21 AM, gavrilyak wrote:
> JS shell supports #!/usr/bin/js , so I just "chmod a+x script.js" and
> run it
> from command line, same way as with bash or python or whatever.

That's a great point, IMO. Added in the latest patch, bound as
scriptArgs on the shell global.

- Leary