Change help to SingleMetavarFormatter

[jyn514]

The default help formatter shows choices twice. This is hard to read if there are many choices. I made a custom class for this in utils, but it has to be specified for every parser individually with formatter_class.

[jyn514]

example in existing code

[jyn514]

example output (first is default, second is with SingleMetavarFormatter)

$ python -m gradeforge download -h      
usage: gradeforge download [-h] [--verbose] [--quiet]
                           [--season {fall,summer,spring}]
                           [--year {2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018}]
                           {sections,bookstore,catalog,exam,grades} ...

download files from sc.edu

positional arguments:
  {sections,bookstore,catalog,exam,grades}

optional arguments:
  -h, --help            show this help message and exit
  --verbose, --debug, -v
  --quiet, -q
  --season {fall,summer,spring}, -s {fall,summer,spring}
  --year {2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018}, -y {2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018}

$ python -m gradeforge download sections -h
usage: gradeforge download sections [-h]
                                    [--campus {AIK,BFT,COL,LAN,SAL,SMT,UNI,UPS,%}]
                                    [--term {%,1A,1B,10,2A,2B,20,3A,3B,30,4A,4B,40,50,6A,6B,60,7A,7B,70,8A,8B,80}]

course sections offered

optional arguments:
  -h, --help            show this help message and exit
  --campus, -c {AIK,BFT,COL,LAN,SAL,SMT,UNI,UPS,%}
  --term, -T {%,1A,1B,10,2A,2B,20,3A,3B,30,4A,4B,40,50,6A,6B,60,7A,7B,70,8A,8B,80}

[charlesdaniels]

@jyn514 I can handle this issue as soon as I have bandwidth available (hopefully within the next few days). Feel free to unassign yourself if you would like.

[charlesdaniels]

Opened PR #39