Confusing example and behavior regarding If(...).Then(() => ...)

[alexrp]

The docs have this example:

Func<long, bool> isZero = Lambda<Func<long, bool>>(fun => 
{
    var arg = fun[0];
    If((Expression)(arg.AsDynamic() != 0L))
        .Then(() => Return(true))
        .Else(() => Return(false))
    .End();
}).Compile();

Is this doing what it's supposed to be doing? Trying this locally, .Then(() => ...) binds to ConditionalBuilder.Then(Expression), not CodeGenerator.Then(ConditionalBuilder, Action). This also makes the API a bit unwieldy in general, since I have to write code with casts like this:

If(...)
    .Then((Action)(() =>
    {
        // ...
    }))
.End()

Not sure if I'm misunderstanding something or if this is unintended. 🤔

[sakno]

Thanks to MS, they introduced breaking change. See dotnet/csharplang#5157. If you have any suggestions, I'm ready to discuss.

[sakno]

Another interesting observation: C# differently resolves ambiguity between extension method and class method. I can replace Then(Action) extension method with class method declared directly in ConditionalBuilder class. In that case, C# resolves overload correctly.

[alexrp]

Interesting, I wasn't aware this was a breaking change in the language.

What do you think about ThenBlock(Action)/ElseBlock(Action) methods as a workaround? Similar idea to what you suggested, but a bit less verbose.

[sakno]

I've fixed this through moving extension methods to class methods. See e6c7499. There is no good solution (without breaking changes). The change I made provides backward compatibility at source level (you need to rebuild the project w/o any changes) but not binary compatibility. ThenBlock is an option, but this is both source and binary incompatible change.

[sakno]

A new release 4.15.0 has been published. @alexrp , could you please mark this discussion as answered?

[alexrp]

I actually tried to do that earlier, but I don't see the option to do it for some reason. 🤔