This issue was originally filed by andrew.m...@gmail.com

I propose to add a new language construct.
This can be treated at least as the statement.
Or in the best case it can be treated as the expression.

I am talking about a modified design "with(object){}".
The proposed innovation is "object.{}".

Examples of the practical application.

// When subject implementation is only statement
html = new HtmlBuilder();
html .{
  head .{
    title = 'Page title';
  }

  body .{

    input .{
      attributes = {'type': 'button', 'value': 'Click me!'}
    }

    table .{
      for(var item in items) {
         rows.add() .{
            cells.add() .{
              innerHtml = escape(item.text);
            }
         }
      }
    }
  }
}

// Another example
var cfg = new CfgBuilder();
cfg .{
  bits = '0';

  compiler .{
    includes = ['{$DART_SDK}/include'];
    inputFiles = ['sample_extension.cc'];
  }

  clean = [ '.exp', '.lib', '.o', '.obj'];

  platforms .{

    linux .{
      compiler .{
        arguments = ['-fPIC', '-Wall'];
      }

      linker .{
        arguments = ['-dynamiclib', '-undefined', 'dynamic_lookup'];
        output_file = 'libsample_extension.dylib';
      }
    }

    macos .{
      compiler .{
        arguments = ['-fPIC', '-Wall'];
      }

      linker .{
        arguments = ['-dynamiclib', '-undefined', 'dynamic_lookup'];
        output_file = 'libsample_extension.dylib';
      }
    }

  windows .{
    compiler .{
      defines = {'DART_SHARED_LIB':};
      input_files = ['sample_extension_dllmain_win.cc'];
    }

    linker .{
      arguments = ['/DLL'];

      input_files .{
         add('dart.lib');
         add('sample_extension_dllmain_win');
      }

      libpaths = ['{$DART_SDK}/bin'];
      output_file = 'sample_extension.dll';
    }
  }
}

// And expmles when subject realizing both options as statements and expressions

var person = new Person() .{
  name = 'John';
  city = 'London';
  print(name);
};

foo() => new Person().{ name = 'John'; city = 'London'; };

print(person.runtimeType == person.{ /**/ }.runtimeType); // true

var obj1 = obj2.{ /* use obj2 / }.{ / use obj2 / }.{ / use obj2 */ };