Allow use of as and is on arbitrary expressions, not just the parameter

[zspitz]

Currently, as is defined as taking only one argument: the type name; it can only be applied to the parameter. This:

class Foo {}
class Bar : Foo {}
class Baz {
    public Foo Foo1 {get;set;} = new Bar();
}

var selector = $"as(\"{typeof(Bar).FullName}\")";

is defined as the equivalent of:

x => x as Bar;

But there is no way to express the equivalent of the following:

Expression<Func<Baz, Bar>> expr = x => x.Foo1 as Bar;

Either of the following:

var selector = $"as(Foo1, \"{typeof(Bar).FullName}\")";
var selector = $"as(\"{typeof(Bar).FullName}\", Foo1)";

fails with:

System.Linq.Dynamic.Core.Exceptions.ParseException: 'The 'as' function requires one argument'

---

The same thing applies to is. Either of the following:

var selector = $"is(Foo1, \"{typeof(Bar).FullName}\")";
var selector = $"is(\"{typeof(Bar).FullName}\", Foo1)";

fails with the above error.

[StefH]

Hello @zspitz ,

For this moment it needs to be a constant value (Type or string).

This question is also related #459.

Closing this issue.

[zspitz]

This has now been fixed with #567, see #566.

[zspitz]

For this moment it needs to be a constant value (Type or string).

@StefH Note that this issue is unrelated to passing the type/string as a parameter object to the Dynamic Linq expression; this issue is about applying as/is to an arbitrary expression.