improve OptionParser?

[derek]

Hi, I'm a new in Erlang/Elixir with somewhat good Python background,
trying to write some small shell utils in Elixir exs script and am
surprised the OptionParser is limited and totally missing in Erlang
standard lib, I read somewhat rebar code and it's using the
`jcomellas/getopt` [3] solution, but I prefer a in lib solution,

Problems with current Elixir OptionParser:
1. it doesn't support combine switches, like "-vn" should be treated
same as "-v -n" if both are not requiring an argument;
2. I need to count behaviour like the Python argparser
`action="count"`; it will be useful to support "--verbose" or "-vvv"
to mean increased verbosity

parser.add_argument("-v", "--verbosity", action="count",
help="increase output verbosity")


[1] http://elixir-lang.org/docs/master/elixir/OptionParser.html
[2] https://github.com/elixir-lang/elixir/blob/master/lib/elixir/lib/option_parser.ex
[3] https://github.com/jcomellas/getopt
[4] https://docs.python.org/2/howto/argparse.html

I'm trying to improve OptionParser, have some local changes in
option_parser.ex, basically I hope it can be as powerful as Python
argparse module [4]; would like to see here if you have some more
ideas,


Thanks,

[José Valim]

Yes, improvements to the action parser will be really welcome. Feel free to expand on your proposals here and send PRs. For example, :count could be done in the existing :switches configuration. I would also be ok with support -vn and the like.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

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[Chris Keele]

Currently only single-letter aliases are allowed. Is this intentional or would the capacity to alias, for instance, option "foo" as "bar" be a welcome PR?

[Amos King]

What is the use case?

Amos King

Binary Noggin

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[Chris Keele]

This was mostly just surprising, not problematic, behaviour.

I have switch of type :keep called :type where you can choose the type of thing to create. You can create many things in one go by passing --type foo --type bar, but it reads well when creating one thing to just say --new thing. 

I could unify the two syntaxes with no extra logic by aliasing :type as :new.

[José Valim]

The reason only single letters are allowed is to support the sort of shortcut that's common on Unix command lines. For example, if you have two aliases named -f and -a, you can pass them as -fa. I believe we could still support multi letter aliases but probably not worth the added complexity. If you really need multi letter aliases, you can always do a prepass on the args and expand them.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

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