node: add support for --interactive-eval (-ie) flag

[Fishrock123]

Fixes#1197

This achieves the desired -ie behaviour of pre-loading the eval expression into, and opening the repl.

iojs -ie "var life = 42"
undefined
> life
42
> 

iojs -ie "console.log('hello world')"
hello world
undefined
> 

I'll setup a test in test-repl-options if this looks reasonable, also, not sure if this needs to be documented in --help or not.

Edit: another thing, what subsystem: should this be?

/cc @bnoordhuis
/first time I've ever touched C++ \o/

[Fishrock123]

Oh, looks like I should also add some doc in repl.markdown...

hmm, options.domain is not documented there either..

[silverwind]

Maybe change --help to just always enter the REPL? Would also remove the only multi-line help :)

[rvagg]

I'm not a fan of the multi-char short version where -ie means a specific thing and not a combination of things. -pe sucks as a special case but it's effectively -p and -e whereas you've framed -i and -e as a single thing, particularly by adding the long-hand version of it --interactive-eval.

The commandline arg parser is a bit too simplistic at the moment and this makes it less POSIX friendly, you should be able to combine arguments and have it make sense, what would -pie do? I would expect that adding pi and e together make something (and not just FOOD).

Perhaps -i needs to be about dropping into a REPL, in which case maybe -r makes more sense? -pie would make sense then as a combination of -pe and a repl. But note that we'd have to tokenizing these args properly.

Basically, I'm a soft -1 on this because I can see the headache of improving our command-line arg parsing at some point in the future when -ie is an single thing and not a strict combination of two things. Am I making sense?

[silverwind]

I agree, hardcoding stuff like -pe and -ie isn't really great. I'd prefer that the parser is flexible enough to detect joined args, so -ep and -ei also work for example. If certain combinations of args make no sense, we should probably error out before trying to guess what the user meant.

[Fishrock123]

Basically, I'm a soft -1 on this because I can see the headache of improving our command-line arg parsing at some point in the future when -ie is an single thing and not a strict combination of two things.

I agree with that. I was actually quite surprised to find these things were hardcoded.

I'd say -ie is a combination of the two, but simply enabling both under the hood doesn't (won't) work. (edit: actually, it probably could). I didn't really know how to change the long-hand arguments to match that.