[Python-Dev] anyone tried to use optparse with something else than sys.argv?

[Erik Heneryd]

hi

snuck a peek at the newly included optparse module yesterday and it seems
option parsing will be a breeze in the future.  good work!

however, imho, it seems a bit too focused on initial sys.argv parsing.
for anything else, you basically have to subclass OptionParser etc to do
anything useful.

for example, you can supply your own argument list to the parse_args()
method, but the autohelp/version/error reporters still use sys.argv[0] as
command name (probably not what you want).  the way optparse gets the
command name (a global function) indicates that you're not supposed to
override it?

also, even if you tell OptionParser to use your user defined Option class
(as explained in the docs: op = OptionParser(option_class=MyOption)), it
still adds standard Option instances to handle autohelp/version.

per default, the autohelp/version/error handlers call sys.exit().  the
docs says that if you want to change this behaviour, simply subclass
OptionParser and/or Option and override/extend the corresponding methods.
ofcourse, this has no effect, since standard instances are used.

also, supressing the actual printing of autohelp/version/error requires
subclassing OptionParser and Option (or sys.stdout = StringIO fiddling).

so?  some minor glitches and (imho) annoyances, whats the deal?

well, to me, it's pretty obvious that the design effort on optparse has
pretty much been focused strictly on initial sys.argv parsing and while
it's extendable, other use cases (embedded consoles etc) seem to have been
given little or no real thought.

the things i mention is probably easy to fix:

* make parse_args() take the whole "sys.argv" list and use the first
element as the command name.  breaks backward compatibility, i know.
why was sys.argv[1:] used in the first place?  the getopt legacy?

* add parse_args_ex() that raises an exception containing the help/error
message instead of SystemExit (SystemExit containing something means
something went wrong, don't it?)

* (simple bug) dynamically populate the OptionParser using the
option_class and not some pre-made Option.

* (simple bug) replace all %prog in help texts etc, not just the first
occurance.


        erik