A read-only, dict-like optparse.Value
Hi folks, Would anybody support the idea of read-only dict-like behaviour of "options" for the following code: ==== from optparse import OptionParser parser = OptionParser() parser.add_option("--host", dest="host" default="localhost") parser.add_option("--port", dest="port", default=1234) parser.add_option("--path", dest="path", default="/tmp") options, args = parser.parse_args() ==== As it is, you have to "know" what possible attributes are present on the options (effectively the set of "dest" attributes) -- I often implement something like the following because recently I've had to use command line options in a bunch of format strings: def make_options_dict(options): known_options = ("host", "port", "path") return dict(zip(known_options, [getattr(options, attr) for attr in known_options])) I don't mind having to do this, but having to hard code the options in there feels a bit nasty. Just as useful for my particular use case (i.e passing the options "dict" to a format string) would be something along the lines of options.todict() or dict(options). Even a way to know the set of "dest" attributes that are defined on "options" would be cleaner. e.g. options_dict = dict(zip(options.all(), [getattr(options, attr) for attr in options.all()])) Where options.all() returns all the option "dest" attribute names. Or something to that effect. Any thoughts? Cheers, T
Thomas Lee
Hi folks,
Would anybody support the idea of read-only dict-like behaviour of "options" for the following code:
====
from optparse import OptionParser parser = OptionParser() parser.add_option("--host", dest="host" default="localhost") parser.add_option("--port", dest="port", default=1234) parser.add_option("--path", dest="path", default="/tmp") options, args = parser.parse_args()
====
I presume you know that dest is redundant there? I ask because you wanted to avoid retyping the option names later :)
As it is, you have to "know" what possible attributes are present on the options (effectively the set of "dest" attributes) -- I often implement something like the following because recently I've had to use command line options in a bunch of format strings:
def make_options_dict(options): known_options = ("host", "port", "path") return dict(zip(known_options, [getattr(options, attr) for attr in known_options]))
I don't mind having to do this, but having to hard code the options in there feels a bit nasty. Just as useful for my particular use case (i.e passing the options "dict" to a format string) would be something along the lines of options.todict() or dict(options). Even a way to know the set of "dest" attributes that are defined on "options" would be cleaner. e.g.
Well, given the implementation of optparse, you could do: options.__dict__.items() But exposing the full dictionary interface on options strikes me as a reasonable idea. I don't see any particular reason to make it read-only, either. (NB: The Values class has some...interesting...methods that I wasn't aware of that look somewhat intriguing. And they aren't read-only.)
options_dict = dict(zip(options.all(), [getattr(options, attr) for attr in options.all()]))
Where options.all() returns all the option "dest" attribute names.
Or something to that effect.
Any thoughts?
I don't see any reason not to just duck type the options object as dictionary-like and use the normal dictionary method names to access the information you want. Off the cuff it seems like a good idea to expose an interface to this information. Hmm. Then I could do globals().update(options.items()), which would simplify some of my code :) (Whether or not that is a good idea is a different question!) -- R. David Murray http://www.bitdance.com
Thomas Lee schrieb:
Hi folks,
Would anybody support the idea of read-only dict-like behaviour of "options" for the following code:
====
from optparse import OptionParser parser = OptionParser() parser.add_option("--host", dest="host" default="localhost") parser.add_option("--port", dest="port", default=1234) parser.add_option("--path", dest="path", default="/tmp") options, args = parser.parse_args()
====
As it is, you have to "know" what possible attributes are present on the options (effectively the set of "dest" attributes) -- I often implement something like the following because recently I've had to use command line options in a bunch of format strings:
def make_options_dict(options): known_options = ("host", "port", "path") return dict(zip(known_options, [getattr(options, attr) for attr in known_options]))
Perhaps options_dict = vars(options) already does what you want? optparse seems to set nonpresent attributes for options to None. Georg -- Thus spake the Lord: Thou shalt indent with four spaces. No more, no less. Four shall be the number of spaces thou shalt indent, and the number of thy indenting shall be four. Eight shalt thou not indent, nor either indent thou two, excepting that thou then proceed to four. Tabs are right out.
Thanks Georg, this is pretty much exactly what I was looking for. Somehow I had never heard of the vars builtin before! Regards, Tom Georg Brandl wrote:
Thomas Lee schrieb:
Hi folks,
Would anybody support the idea of read-only dict-like behaviour of "options" for the following code:
====
from optparse import OptionParser parser = OptionParser() parser.add_option("--host", dest="host" default="localhost") parser.add_option("--port", dest="port", default=1234) parser.add_option("--path", dest="path", default="/tmp") options, args = parser.parse_args()
====
As it is, you have to "know" what possible attributes are present on the options (effectively the set of "dest" attributes) -- I often implement something like the following because recently I've had to use command line options in a bunch of format strings:
def make_options_dict(options): known_options = ("host", "port", "path") return dict(zip(known_options, [getattr(options, attr) for attr in known_options]))
Perhaps
options_dict = vars(options)
already does what you want? optparse seems to set nonpresent attributes for options to None.
Georg
participants (3)
-
Georg Brandl -
R. David Murray -
Thomas Lee