Cannot make use of optional arguments declared in a library

[Charles]

The optional argument support in Cobra doesn't work across libraries. In other words, if the method is declared like so:

class X

    def foo(verbose = false) as int
        return if(verbose, 1, 0)   

Then trying to invoke the method without an argument will work in the same code base, but fail in another project with:

error: The method "foo" is expecting 1 argument, but no arguments are being supplied in this call. The declaration is "foo(verbose as bool)"

This all came up because I tried using optional args in Cobra.Core after which some test cases failed the above error.

The solution will almost certainly be the generation and scanning of attributes on the argument. Ideally, we would use the same conventions as the C# compiler for maximum compatibility between Cobra and C#.

[Charles]

Not that we're trying to get things working on .NET < 4, but when I went looking too see what if any attributes the C# compile uses, I came across this:
 http://stackoverflow.com/questions/5116340/c-sharp-3-5-optional-and-defaultvalue-for-parameters

[Charles]

It turns out that .NET has had this feature for a long time and longer than C#. Reflection already covers this:

"""
ParameterInfo
    .isOptional
    .hasDefaultValue
    .defaultValue

    per http://msdn.microsoft.com/en-us/library/system.reflection.parameterinfo.aspx
"""

use System.Reflection

class X

    def one(a as int, b as int)
        pass
        
    def two(a as int, b as int = 5)
        pass

    def main is shared
        t = X
        for mi in t.getMethods(BindingFlags(Public, Instance, DeclaredOnly))
            trace mi
            for pi in mi.getParameters
                trace pi, pi.hasDefaultValue, pi.isOptional
                if pi.hasDefaultValue, trace pi.defaultValue

[Charles]

I got this.

[Charles]

Fixed in changeset:3063

[nerdzero]

Careful, I think .hasDefaultValue is from 4.5

[Charles]

Wow, thanks for the catch!

[Charles]

Dependency removed. My external test still works. Ran whole test suite.

changeset:3065