[yt-dev] Arguments to scripts

Fri Dec 2 11:57:49 PST 2011

That's the big problem, yes.  I would be fine with yt taking over
things like "--help" and whatnot, which are reserved.  But I would
also note that we're actually *changing* the functionality, not
*removing* it if we go with 2+4.  It says, if you want your script to
be able to run in parallel yt, or to use these yt commands, here's how
you interface with the yt argument parsing.

On Fri, Dec 2, 2011 at 2:51 PM, Britton Smith <brittonsmith at gmail.com> wrote:
> I think I still prefer option 3.  I'm in favor of making the system of
> parsing yt args cleaner, but options 1, 2, and 4 feel to me like we're
> saying in order to use yt, you have to trade in some python functionality
> that you've been using.  Is the only reason we wouldn't go with option 3
> that it will not catch typos in flags that we intended to be for yt?
>
> Britton
>
> On Fri, Dec 2, 2011 at 1:39 PM, david collins <antpuncher at gmail.com> wrote:
>>
>> > Talking this through leads me to think we might be able to have a
>> > combination of 4 and 2.  I just tested and what we *can* do is
>> > actually provide the parser arguments as above, but allow for a
>> > "leftovers" section for all *positional* arguments to the script.
>> > This would mean for --something and -s arguments you would need to add
>> > those to the parser object, but for things like what you do above, you
>> > wouldn't.
>> >
>> > Would that work for your use case?
>>
>> So is option 4 something like
>>
>> <myscript>
>> import yt
>> if __name__ == "__main__":
>>   yt_option_parser.add_option("--clown_hair_size_threshold")
>>   do some stuff using the clow hair size
>> </myscript>
>>
>> like a modified/subclassed optparse?  Then my command line is like
>> mpirun -np 16127 python myscript --clown_hair 14 --parallel
>> ?
>>
>> In your "leftovers" version of Option 2, could that just modify
>> sys.argv in place, pop-ing out the bits that yt wants or wants to
>> raise an error on?  Not strictly necessary, but it would mean a little
>> less modification of old scripts on my part.  (Though frankly, scripts
>> where I use sys.argv directly should be thrown in the toilet, so
>> forcing me to re-write those tools to use some less fragile option
>> parser is probably good for me.)
>>
>> Anyhow, as long as it still retains the ability for me to pass in
>> non-yt options to the script, I'm happy.  And there are certainly
>> bigger concerns here than my army of dumb scripts.  The first version
>> of option
>> 2 wouldn't really do that, but the 'leftovers' version would.  I think
>> I like your new 2 + 4.
>>
>> d.
>>
>>
>> >
>> > -Matt
>> >
>> >>
>> >> Additionally, if I use optparse, similar outcomes?
>> >>
>> >> d.
>> >>
>> >>
>> >> On Fri, Dec 2, 2011 at 9:30 AM, Matthew Turk <matthewturk at gmail.com>
>> >> wrote:
>> >>> Hi all,
>> >>>
>> >>> I have prepared a Pull Request to change how yt processes arguments to
>> >>> scripts.  I just issued it, but I am emailing because I think
>> >>> discussion of what it does warrants a bit more public hashing out.
>> >>> The PR is not done yet, for the reasons I outline below, so please
>> >>> don't anybody accept it yet.
>> >>>
>> >>>
>> >>> https://bitbucket.org/yt_analysis/yt/pull-request/38/overhaul-configuration-system
>> >>>
>> >>> This will directly affect you if you have:
>> >>>
>> >>> 1) Ever written "from yt.config import ytcfg; ytcfg[...."
>> >>> 2) Ever put your *own* command-line parser into yt.
>> >>> 3) Gotten annoyed with configuration files.
>> >>>
>> >>> What I've done is create a new file, startup_tasks.py, that gets
>> >>> imported whenever yt.mods gets imported, and only the first time that
>> >>> happens.  It sets up an argument parser (using argparse, which is
>> >>> Python 2.7 only) that parses looking for:
>> >>>
>> >>> --parallel
>> >>> --paste
>> >>> --paste-detailed
>> >>> --detailed
>> >>> --rpdb
>> >>> --parallel
>> >>>
>> >>> One of the things this does is that it also provides --help, so you
>> >>> can see what is available.  Furthermore, I've added a --config option,
>> >>> so that from the command line you can set configuration options.  For
>> >>> instance:
>> >>>
>> >>> --config serialize=False
>> >>>
>> >>> and so on.  This is pretty cool I think and will go a long way toward
>> >>> making things nicer.  However, the way this works is still up for a
>> >>> few more problems.  There are basically two ways this can work:
>> >>>
>> >>>  * Parse the entirety of sys.args and accept all arguments that yt
>> >>> finds, rejecting and throwing an error on unrecognized ones (i.e.,
>> >>> typos or things you might pass in to a script your write on the
>> >>> command line).  This will be an exclusive operation.
>> >>>  * Parse *non-exclusively*, allowing unrecognized arguments to pass
>> >>> through.  However, the old arguments will still be there: so any
>> >>> script that has issues with things like --parallel and whatnot will
>> >>> now see there, whereas it did not before because yt (totally un-cool!)
>> >>> stripped them out of the sys.args variable.  I don't want to do this
>> >>> anymore.
>> >>>
>> >>> The way I have implemented this for the yt command line tool is to set
>> >>> a flag that says, "We're also inside the command line, so don't parse
>> >>> anything, we'll handle adding new options to the parser and then we'll
>> >>> parse everything at the end."  This way you can pass both --parallel
>> >>> and whatever option the yt command line utility wants.  This works
>> >>> because startup_tasks creates a "parser" object, adds arguments to
>> >>> that parser object, then delays actually conducting the parsing until
>> >>> all the arguments from teh command line tool have been added.
>> >>>
>> >>> There are four ways this can work.  I have presented them in order of
>> >>> my increasing preference.  (Coincidentally, on the astropy mailing
>> >>> list they discussed this this week, as I was thinking about my
>> >>> feelings on it as well, and they are moving away from parsing args in
>> >>> the library; I think that works for them because AstroPy is designed
>> >>> to be used much more inside larger frameworks, whereas yt is somewhat
>> >>> more insular.)
>> >>> 1) Don't do any argument parsing if not called through a yt-specific
>> >>> script runner.  This means if you want to pass --parallel, you have to
>> >>> run with something like "yt run my_script.py --parallel".  Same for
>> >>> --config and so on.
>> >>> 2) Parse all arguments any time yt.mods is imported, do not allow for
>> >>> additional arguments.  This breaks scripts that have their own
>> >>> parsing.
>> >>> 3) Parse *some* of the arguments, but not all.  All typos would
>> >>> succeed and this could lead to confusion for the user.
>> >>> 4) Provide a yt-specific mechanism for adding new arguments.  So if
>> >>> you want to add new arguments, you do it at the top of your script,
>> >>> rather than the bottom, and at the bottom inside the construction "if
>> >>> __name__ == '__main__'" you'd inspect the values.
>> >>>
>> >>> Anyway, I'm inclined to go for #4, simply because it would be the
>> >>> simplest mechanism for ensuring an explicit method of getting
>> >>> arguments into user-written scripts.
>> >>>
>> >>> Thoughts?
>> >>>
>> >>> -Matt
>> >>> _______________________________________________
>> >>> yt-dev mailing list
>> >>> yt-dev at lists.spacepope.org
>> >>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>> >>
>> >>
>> >>
>> >> --
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>>
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