Custom formatters for optional arguments

[Jonathan Soma]

I'm attempting to use Gooey with mapshaper, but unfortunately mapshaper requires all sorts of wild formatting for its arguments, separated between values, flags, and key/value pairs.

For example:

mapshaper provinces.shp -simplify dp 20% -o format=geojson out.json

This is currently not possible with Gooey. Not to mention something more complex, like

mapshaper -i 'cb_2020_us_county_500k.shp' \
    -each 'JOIN_FIPS="USA-" + GEOID' \
    --join 'us-counties-recent.csv' keys=JOIN_FIPS,geoid \
    -classify field=cases_avg_per_100k save-as=fill \
    colors=Magma invert breaks=10,30,50,70,100,250 \
    -proj 'albersusa' \
    -simplify '2%' \
    -o 'out.svg'

Allowing customization of how each widget's output is formatted on the command line could go a long way in letting Gooey support similarly strange approaches to CLI tooling. Pull request incoming to try and enable support for this.