Option callback is not called if optional value is not defined

[kirbysayshi]

Hopefully the title isn't too confusing :)

I have an option

.option('-c, --chart [columns]', 'Add columns', splitOrDefault, false)

• If --chart is not present, I would want the value to be false.
• If it is present, but [columns] are not, I want to default it to something like ['col1', 'col2'].
• If something like --chart col1,col2,col3 is passed, I want those values to take precedence.

Unfortunately, the option value callback (splitOrDefault above) is not called if the value is undefined, and thus I cannot check for --chart being defined but not [columns], and it's just defaulted to false.

Given line 332, I get that this callback behavior is intended, but wanted to discuss before submitting a PR.

I may be asking for too much from commander, or there might be a simpler way... is this possible?

[abetomo]

Closing due to possible answer suggested and no response registered. Feel free to comment and we can re-open in case this issue persisted.

[shadowspawn]

Options with optional arguments and a default value were broken before Commander 9. This will be possible with proposed changes in #1652