Change in parsing behaviour between 6 and beta7

[barrygiles]

I'm trying to understand the change in behaviour I'm seeing around parsing with the move from beta6 to beta7.

Specific library changes:
from 2.0.0-beta6.25351.105
to 2.0.0-beta7.25353.2

The issue I'm seeing seems like it's related to boolean values, but might not be limited to those.

It seems like on the earlier version, boolean options would show as having a default value if the DefaultValueFactory was set. This seems to have changed now, so that when I inspect the parse result, it looks like all boolean values have been set with a default, which seems less helpful to me. It gives the impression that these values have been set somehow, either through the command line or with an explicit default value.

e.g. for the command: mycommand subcommand --verbose
where --no-color has DefaultValueFactory set

Before: Parse result: [ mycommand [ subcommand [ --verbose ] *[ --no-color ] ]
After: Parse result: [ mycommand [ subcommand [ --verbose ] *[ --quiet ] *[ --no-interactive ] *[ --no-color ] ]

I had an extension method for checking whether an option is set, which I was using to see if both --quiet and --verbose were set, which is now not working properly.

public static Boolean HasOption(this SymbolResult symbolResult, Option option) =>
symbolResult.GetResult(option) is not null || option.HasDefaultValue;

Is this a bug? And if not, could someone help explain the change in behaviour please?

[barrygiles]

Looks like it's related to #2601

[elgonzo]

As your second comment seems to indicate that you found the answer to your question, can this be closed or is there still an issue you want to address?

By the way, checking whether an option was given on the commandline or not can be done using the OptionResult.Implicit property:

public static bool HasOption(this SymbolResult symbolResult, Option option)
    => symbolResult.GetResult(option) is OptionResult optResult && !optResult.Implicit;

or shorter without pattern matching, but reading a little unusual (because evaluating bool?):

public static bool HasOption(this SymbolResult symbolResult, Option option)
    => symbolResult.GetResult(option)?.Implicit == false;

[barrygiles]

Thanks for your response elgonzo. Hmm I'm not sure atm, I referenced that more for context but haven't had time to read through it all just yet.

Thanks for that proposal - let me give that a go and read through the linked PR in more detail and I'll come back to this.

[jonsequitur]

The change in behavior was to give Option<bool> a DefaultValueFactory (which you can overwrite). The default value is false.

By the way, checking whether an option was given on the commandline or not can be done using the OptionResult.Implicit property:

This is the recommended way to check whether something was actually parsed from command line input.

[barrygiles]

Thanks for the comments. That change to HasOptions has things working again. Not sure why I used option.HasDefaultValue there. Now I'm wondering what the difference between Implicit and HasDefaultValue is...

So functionally looks like there's no regression - it was a bug with my helper method.

I've been logging out the parseResult during developement which I've found really useful. It seems less clear to me what's going on now with this change, having every boolean option look like it was provided.

In the case of booleans with zero arity, the presence of those options in the parse result previously indicated that they were set. Not the end of the world, but if this were extended to other option types, then the benefit of viewing the parse result would seem to be lost as it would look like everything is supplied all the time.

In terms of overwriting the DefaultValueFactory, I was curious if I could do this by setting it to null, but that seems to have no effect. I suppose I'd have to set it to function, but I don't think that would affect what I'm raising about the parse result.

May well be quite subjective and particular to me and/or confusion on my part.

[jonsequitur]

When you see * in the output of ParseResult.ToString() it indicates that the option was implicit. Since Option<bool> now always has a default value, these will always show up in the diagram.

An alternative or improved diagram format wouldn't be very difficult to write. The one that's there has been in place for a long time but hasn't gotten a lot of feedback over the years.

[barrygiles]

Thanks for the comments - the original issue was user error, happy for this to be closed.