Dynamically assigning properties on plain javascript objects - tricky

Hi,

I was hoping to be able to convert a [<String->Object>*] to a properties of a plain javascript object, but bumped into some problems.

So the first attempt is:

dynamic JSObject {}
JSObject? toObj([<String->Object>*] props) {
    dynamic obj;
    dynamic {
        obj = dynamic [];
    }
    for (k->v in props) {
        dynamic {
            obj[k] = v;
        }
    }
    dynamic {
        return obj;
    }
}

but that didn’t work, I get an error Expression cannot be assigned for the obj[k] = v; line. Next I try to replace that line with a bit of javascript:

           eval("(function(o,k,v){o[k]=v})")(obj, k, v);

Now I instead get the error (same error as in #5808 btw):

The GenerateJsVisitor caused an exception visiting a InvocationExpression node: "java.lang.NullPointerException" at com.redhat.ceylon.compiler.js.InvocationGenerator.positionalInvocation(InvocationGenerator.java:182)"

Finally I put the eval-generated function in a temporary variable and this works:

            dynamic set = eval("(function(o,k,v){o[k]=v})");
            set(obj, k, v);

I’m guessing all of my approaches should work. Also if you happen to know a pre-existing function to does what I’m doing, let me know 😃

[chochos]

with #4148 I added support for the x[foo]=bar syntax and it can now be used on plain JS objects inside dynamic blocks.

[bjansen]

This gist could become the beginning of a new ceylon.interop.js module…