#55 Added StrongDefaultValue for ValueArgument

[eapyl]

As it is described in #55

[twpol]

I think this change means that many (all?) existing uses of DefaultValue now have to use ForcedDefaultValue, which caused me quite a lot of confusion when updating the version of CommandLineParser just now. I can raise an issue with full details and code if you need it.

[StefH]

Sorry for the confusion. Please raise an issue with the usage differences for before/after this code.

[alexandre-lecoq]

I have the same issue. However, my understanding is that it's not really a bug, but rather an unconscious and unadvertised breaking change. Also could not find anything about ForceDefaultValue in the documentation.

Basically, i had this code :

        [ValueArgument(
            typeof(int),
            "connectiontimeout",
            DefaultValue = 5,
            Description = "The time to wait for a connection to open.",
            FullDescription = "The time (in seconds) to wait for a connection to open. The default value is 5 seconds.",
            Example = "15")]
        public int ConnectionTimeout { get; set; }

This code would behave like this :

• No "--connectiontimeout" passed => ConnectionTimeout = 5
• "--connectiontimeout 10" passed => ConnectionTimeout = 10

Now with the introduction of ForceDefaultValue the code behaves like :

• No "--connectiontimeout" passed => ConnectionTimeout = 0
• "--connectiontimeout 10" passed => ConnectionTimeout = 10

This is how it broke my application. My understanding, is that there is a change of semantic of DefaultValue. It was the default value for both the lack of passed parameter and the lack of value for a passed parameter. It seems to me, now, those 2 cases are split :

• ForceDefaultValue is used for the lack of passed parameter
• DefaultValue is used for the lack of value for a passed parameter

Therefore if I understand correcly, in the latest version, I to change my code to :

        [ValueArgument(
            typeof(int),
            "connectiontimeout",
            DefaultValue = 5,
            ForcedDefaultValue = 5,
            Description = "The time to wait for a connection to open.",
            FullDescription = "The time (in seconds) to wait for a connection to open. The default value is 5 seconds.",
            Example = "15")]
        public int ConnectionTimeout { get; set; }

That is, for ValueArgument, if I want to keep the old behavior, wherever I have DefaultValue, I now have to also add ForcedDefaultValue.

Can you confirm ?

I'm not raising an issue because I think there's no (simple) going back except reverting the new feature. It would have been nice to document the change and change the major version number of the package though.

[StefH]

Thank you for this information. I will try to understand and investigate the code and see if I can bring the old behaviour back.

[alexandre-lecoq]

I think the cause is here : https://github.com/j-maly/CommandLineParser/blob/40120ac02a670dae0ace4e21103d97be370ad46e/src/CommandLineArgumentsParser/Arguments/ValueArgument.cs#L428

[alexandre-lecoq]

I proposed a fix in PR #68