--no is bugged with default arguments

[Zamiell]

Hello, and thanks for the useful library.

Consider the following program:

const { program } = require('commander');

program.option('--no-foo', true)
program.option('--no-bar', false)
program.parse();

const options = program.opts();
console.log(options)

Running this program will result in the following output:

{ foo: true, bar: true }

This is a bug, because commander.js is not using the default value that was specified. Specifically, I would expect specifying true for the default value of --no-foo would mean that false should be the default value of --foo, which means that the correct output should be:

{ foo: false, bar: true }

Additionally, I will say that I do not like the special/magic behavior of commander.js to invert my --no arguments. It makes for a more confusing code base, especially when bugs like the above exist! Is there some way to disable this special/magic behavior?

[shadowspawn]

Thanks for the example code.

You are missing the description argument in your example, so the true/false are being read as a description and not a default value.

Try:

program.option('--no-foo', 'foo description', true)
program.option('--no-bar', 'bar description', false)

Is there some way to disable this special/magic behavior?

No, it is a built-in feature which can not be disabled.

(I think you can flip the results by specifying both a default value and a preset value, but I suggest it is not worth the effort!)

[Zamiell]

Sorry about that. With the following program:

const { program } = require('commander');

program.option('--no-foo', 'foo description', true)
program.option('--no-bar', 'bar description', false)
program.parse();

const options = program.opts();
console.log(options)

I get the following output:

{ foo: true, bar: false }

However, as I said above, this output is a bug. Consider the following line:

program.option('--no-foo', 'foo description', true)

When translated to English, this line means: "By default, we want there to be no foo."
Thus, the output should be:

{ foo: false, bar: true }

I understand that Commander.js has magic behavior to transform no-foo --> foo, but this special behavior should also properly flip the default argument as well.

[shadowspawn]

I understand that Commander.js has magic behavior to transform no-foo --> foo, but this special behavior should also properly flip the default argument as well.

Here is another way of describing it. Adding an option with flags --no-foo creates an option named foo. Specifying a default value sets the starting value of option foo, just like with any other option.

I see your interpretation, but it isn't the only interpretation and I don't think is worth considering changing the behaviour. Not least because specifying a default value for a negated option is probably rare.

[Zamiell]

Ok, I will close this issue, thank you.

In the future, a way to disable the magic behavior would be welcome, I see that it was also previously requested here: #979