I'm a little slow, so let me make sure I understand what your suggestions are, or at least put it into context that I use.
Say I have a dumb script that does<dumb> import sys pf = load(sys.argv) pc = PlotCollection(pf,center=[0.5]*3) pc.add_projection("ClownDensity",axis=2) pc.save("Clown2PerCm2") </dumb>
I would typically do something like "mpirun -np 4013 python2.7 dumb.py path --parallel"
For option 1, use of this would only work if I called "mpirun -np 4013 yt run dumb.py path --parallel" instead
For option 2, this wouldn't work at all?
For option 3, this would work as "normal",
and option 4 I'd have to put "path" inside of dumb.py?
Additionally, if I use optparse, similar outcomes?
On Fri, Dec 2, 2011 at 9:30 AM, Matthew Turk email@example.com wrote:
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.
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:
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.
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